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Madhyamik Class 10 Mathematics Solved Paper 2023

Complete WBBSE Class X Mathematics 2023 question paper with accurate, step-by-step solutions.

WBBSEClass XMathematics202390 Marks3 h67 Questions

Question 1 of 67

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Q

Question – 1

Choose the correct answer from the following questions: [1 × 6 = 6]  

Question 1 (i)

1 (i)PartnershipEasy1 Mark

Three friends A, B, and C started a business with capitals ₹ x, 2x and y respectively, at the end of the term profit is ₹ z, then the share of the profit of A is

(a) ₹ \frac{\text{xz}}{\text{3x+y}}

(b) ₹ \frac{\text{2xz}}{\text{3x+y}}

(c) ₹ \frac{\text{z}}{\text{2x+y}}

(d) ₹ \frac{\text{xyz}}{\text{3x+y}}

Answer

(a) ₹ \frac{\text{xz}}{\text{3x+y}}

Explanation

Ratio of the share = x : 2x : y

Total amount = x + 2x + y = 3x + y

Profit = z

A’s profit shares = \text{\text{x}}\over \text{\text{3x + y}} × z

= \frac{\text{xz}}{\text{3x+y}}

Question 1 (ii)

1 (ii)Quadratic Equation With One VariableEasy1 Mark

Number of solutions of equation x2 =  x is

(a) 1

(b) 2

(c) 0

(d) 3

Answer

(b) 2

Explanation

x2 =  x

or, x2 –  x = 0

or, x(x – 1) = 0

or, x = 0 and 1

Question 1 (iii)

1 (iii)Theorem Related to a Tangent To a CircleEasy1 Mark

If two circles touch each other internally, then the number of common tangents of the circles are

(a) 1

(b) 2

(c) 3

(d) 4

Answer

(a) 1

Explanation

When two circles touch each other internally, a single common tangent can be drawn. This tangent touches both circles at their common point of contact.

Question 1 (iv)

1 (iv)Trigonometric Ratios And Trigonometric IdentitiesEasy1 Mark

For any value of θ the maximum value of 5 + 4 sin θ is

(a) 9

(b) 1

(c) 0

(d) 5

Answer

(a) 9

Explanation

5 + 4 sin θ [ax value of sin θ = 1]

= 5 + 4 × 1

= 9

Question 1 (v)

1 (v)SphereEasy1 Mark

If the ratio of the volumes of two solid spheres is 27 : 8, then the ratio of their curved surface area is

(a) 1 : 2

(b) 9 : 4

(c) 1 : 8

(d) 1 : 16

Answer

(b) 9 : 4

Explanation

Given ratio of volumes = 27 : 8

or, 4\over 3πr1³ : 4\over 3πr2³ = 27 : 8

or, r1³ : r2³ = 27 : 8

or, r1 : r2 = 3 : 2

Ratio of volumes = 4πr1² : 4πr2²

= r1² : r2²

= 3² : 2² = 9 : 4

Question 1 (vi)

1 (vi)StatisticsEasy1 Mark

Three values ​​of a variable are 4, 5 and 7, if their frequencies are p – 2, p + 1 and p – 1 respectively and the Mean is 5.4, then the value of p is:

Answer

(d) 4

Explanation

Mean = \frac{∑\text{fx}}{∑\text{f}}

or, 5.4 = \frac{4(p – 2) + 5(p + 1) + 7(p – 1)}{(p – 2) + (p + 1) + (p – 1)}

or, 5.4 = \frac{\text{6p – 10}}{\text{3p – 2}}

or, 16p – 10 = 5.4 (3p – 2)

or, 16p – 16.2p = -10.8 + 10

or, 0.2p = 0.8

or, p = 4

Q

Question – 2

Fill up the blanks (any five): [1 × 5 = 5]

Question 2 (i)

2 (i)Compound InterestEasy1 Mark

The annual rate of compound interest is r% and if the first year principal is P, then the 2nd year principal is ___.

Answer

P(1 + r\over100)

Explanation:

After one year, amount = Principal × (1 + r\over100).

This amount becomes the 2nd year principal.

Question 2 (ii)

2 (ii)Quadratic SurdsEasy1 Mark

If mean proportional of (a2bc) and (4bc) is x, then the value of x is _____.

Answer

± 2abc

Explanation

\text{a²bc}\over \text{x}=\text{x} \over \text{4bc}

or, x² = 4a²b²c²

or, x = √4a²b²c² = ± 2abc

Question 2 (iii)

2 (iii)Trigonometric Ratio of Complementary AngleModerate1 Mark

If tan θ cos 60° = \frac{\sqrt{3}}{2} then the value of sin(θ – 15°) is _____.

Answer

1\over√2.

Explanation

tan θ cos 60° = \frac{\sqrt{3}}{2}

or, tan θ × 1\over 2 = \frac{\sqrt{3}}{2}

or, tan θ = √3

or, tan θ = tan 60º

or, θ = 60º

sin(θ – 15°) = sin(60º – 15°)

= sin 45°

= 1\over√2

Question 2 (iv)

2 (iv)Trigonometric Ratio of Complementary AngleEasy1 Mark

If ∠A and ∠B are complementary then ∠A + ∠B = _____

Answer

90º

Explanation

Two angles are called complementary angles if the sum of their measures is 90 degrees.

So, by definition:

∠A and ∠B are complementary

⇒ ∠A + ∠B = 90°.

Example: If ∠A = 30°, then ∠B = 60°.

30° + 60° = 90°.

Therefore, the answer is 90°.

Question 2 (vi)

2 (vi)StatisticsEasy1 Mark

The median of the numbers 8, 15, 10, 11, 7, 9, 11, 13 and 16 is _____.

Answer

11

Explanation

7, 8, 9, 10, 11, 11, 13, 15, 16

Here n = 9, which is odd

Median = n + 1\over 2 th Observation

= 9 + 1\over 2 th Observation

= 10\over 2 th Observation

= 5th Observation = 11

Question 2 (vi)

2 (vi)Real Life Problems Related To Different Solid ObjectEasy1 Mark

The shape of a pencil with one end sharpened is the combination of a and a _____.

Answer

Cone and Cylinder

Q

Question – 3

Write True or False (any five): [1 × 5 = 5] 

Question 3 (i)

3 (i)Compound InterestEasy1 Mark

State True or False: In the compound interest if the rate of interest in the first three years is r1,%, r2%, 2r3% respectively, then the amount for the principal P at the end of three years is  P \big(1+ \frac{ r_{1} }{100}) \big(1+ \frac{ r_{2} }{100}) \big(1+ \frac{ r_{3}}{100})

Answer

True

Explanation

In the compound interest if the rate of interest in the first three years is r1,%, r2%, 2r3% respectively, then the amount for the principal P at the end of three years is  P \big(1+ \frac{ r_{1} }{100}) \big(1+ \frac{ r_{2} }{100}) \big(1+ \frac{ r_{3}}{100})

Question 3 (ii)

3 (ii)Trigonometric Ratio of Complementary AngleEasy1 Mark

State True or False: The values ​​of cos 36° and sin 54° are equal.

Answer

True

Explanation

sin 54°

= sin (90° – 36°)

= cos 36°

Question 3 (iii)

3 (iii)Theorem Related To CircleEasy1 Mark

State True or False: One tangent can be drawn on a circle from an external point.

Answer

False

Explanation

This statement is false. As maximum of two tangents can be drawn on a circle from an external point

Question 3 (iv)

3 (iv)Ratio And ProportionEasy1 Mark

State True or False: The compound ratio of 2ab : c², bc : a² and ca : 2b2 is 1 : 1.

Answer

True

Explanation

2ab : c², bc : a² and ca : 2b2

= (ab × bc × ca) : (c² × a² × b²)

= c² × a² × b² : c² × a² × b² = 1 : 1

Question 3 (v)

3 (v)SphereModerate1 Mark

State True or False: If the numerical values ​​of the curved surface area and volume of a sphere are equal, then the radius will be 3 units.

Answer

True

Explanation

CSA of sphere = Volume of Sphere

4πr² = 4\over3πr³

or, 1 = 1\over3r

or, r = 3 units

Question 3 (vi)

3 (vi)StatisticsEasy1 Mark

State True or False: The Mode of the data 5, 2, 4, 3, 5, 2, 5, 2, 5, 2 is 2.

Answer

False

Explanation

the mode is 2 as well as 5

Q

Question – 4

Answer the following questions (any ten): [2 × 10 = 20]

Question 4 (i)

4 (i)Simple InterestEasy2 Marks

Find the rate of simple interest per annum when the interest of some money in 5 years will be \frac{2}{5} part of its principal.

Answer

Let the principal be P

SI = 2\over 5 of principal = 2\over 5 P

time (t) = 5 years

Rate = \text{SI} × 100\over \text{P × t} = {2\over 5}\text{P} × 100\over \text{P} × 5 = 8%

Question 4 (ii)

4 (ii)PartnershipEasy2 Marks

In a business capitals of A and B are in the ratio \frac{1}{7} : \frac{1}{4} If they make a profit of ₹ 11,000 at the end of the year, calculate the share of their profit.

Answer

Ratio of capital = \frac{1}{7} : \frac{1}{4}

= 4 : 7

Sum of ratio = 4 + 7 = 11

Profit of A = \frac{4}{11} × 11000 = ₹ 4000

Profit of B = \frac{7}{11} × 11000 = ₹ 7000

Question 4 (iii)

4 (iii)Quadratic Equation With One VariableModerate2 Marks

If the sum of the roots of the equation x² – x = k(2x – 1) is 2, then find the value of K.

Answer

x² – x = k(2x – 1)

or, x² – x = 2kx – k

or, x² – (2k + 1)x + k = 0

Sum of roots = α + β = 2k + 1

ATP : 2k + 1 = 0

k = –\frac{1}{2}

Question 4 (iv)

4 (iv)Quadratic Equation With One VariableEasy2 Marks

Find out the ratio of the sum and the product of two roots of the equation 7x² − 66x + 27 = 0.

Answer

Sum of roots (α + β) = 66\over 7

Produt of root (α β) = 27\over 7

Ratio of the sum and the product of two roots

= 66\over 7 : 27\over 7

= 66 : 27

= 22 : 9

Question 4 (iv)

4 (iv)VariationEasy2 Marks

If b ∝ a³ and a increase in the ratio of 2 : 3, then find in what ratio b will be increasesed .

Answer

b ∝ a³

or, b = ka³

b1 : b2 = ka1³ : ka2³

or, b1 : b2 = 2³ : 3³ = 8 : 27

Hence, b must increase in ratio 8 : 27

Question 4 (v)

4 (v)Theorems Related To Cyclic QuadrilateralModerate2 Marks

AB and CD are two chords of a circle. If we extend BA and DC, they intersect each other at point P. Prove that ∠PCB = ∠PAD.

Answer

Given, AB and CD are two chords of a circle

AB and CD are two chords of a circle. If we extend BA and DC, they intersect each other at point P

ABCD is a cyclic quadrilateral,

So, the opposite angles in a cyclic quadrilateral is equal to 180°

⇒ ∠BCD + ∠BAD = 180°

⇒ ∠BAD = 180° – ∠BCD

⇒ ∠BAD = 180° – ∠PCB — (i) [∵ ∠BCD = ∠PCB]

From the fig, ∠PAD + ∠BAD = 180° (Linear pair)

⇒ ∠PAD = 180° – ∠BAD

From the equation (i)

⇒ ∠PAD = 180° – (180° – ∠PCB)

∴ ∠PAD = ∠PCB (Proved)

Question 4 (vi)

4 (vi)SimilarityEasy2 Marks

In ΔABC, L and M are two points on the sides AC and BC respectively such that LM || AB and AL are (x – 2) units, AC = 2x + 3 units, BM = (x – 3) units and BC = 2x units. Determine the value of x.

Answer

In ΔABC, L and M are two points on the sides AC and BC respectively such that LM || AB and AL are (x - 2) units, AC = 2x + 3 units, BM = (x – 3) units and BC = 2x units

AL = x – 2

AC = 2x + 3

BM = x – 3

BC = 2x

ΔMCL ∼ ΔBCA

\text{AL}\over \text{AC} = \text{BM}\over \text{BC}

or, \text{x – 2}\over \text{2x + 3} = \text{x – 3}\over \text{2x}

or, 2x² – 4x = 2x² – 6x + 3x – 9

or, – 4x + 6x – 3x =-9

or, x = 9

Question 4 (vii)

4 (vii)Theorem Related to a Tangent To a CircleEasy2 Marks

Two circles touch each other externally at point C. A direct common tangent AB touches the two circles at points A and B. Find the value of ∠ACB.

Answer

Given X and Y are two circles touch each other externally at C. AB is the common tangent to the circles X and Y at point A and B respectively.

Two circles touch each other externally at point C

To find: ∠ACB

Proof: Let P be a point on AB such that, PC is at right angles to the line joining the centers of the circles.

Note that, PC is a common tangent to both circles.

This is because the tangent is perpendicular to the radius at the point of contact for any circle.

Let ∠PAC = α and ∠PBC = β.

PA = PC [lengths of the tangents from an external point C]

In a triangle CAP, ∠PAC = ∠ACP = α

Similarly, PB = CP and ∠PCB = ∠CBP = β.

Now in the triangle ACB:

∠CAB + ∠CBA + ∠ACB = 180° [sum of the interior angles in a triangle]

α + β + (α + β) = 180° (Since ∠ACB = ∠ACP + ∠PCB = α + β).

2α + 2β = 180°

⇒  α + β = 90°

∴ ∠ACB = α + β = 90°

Question 4 (viii)

4 (viii)Trigonometric Ratio of Complementary AngleModerate2 Marks

If tan 2A = cot(A – 30°), then find the value of sec(A + 20°)

Answer

tan2A = cot(A − 30°),

We have tan2A = cot(A − 30°)

⇒ cot(90° − 2A) = cot(A − 30°),

⇒ (90° − 2A) = (A − 30°),

⇒ A = 40°

∴ Sec (A + 20°) = 40° + 20°

Sec (60°) = 2

Question 4 (ix)

4 (ix)Trigonometric Ratio of Complementary AngleEasy2 Marks

If tan θ = \frac{8}{15} find the value of sin θ.

Answer

tan θ = \frac{8}{15}

⇒ p = 8k and b = 15k

Pythagoras theorem: h² = p² + b²

or, h² = (8k)² + (15k)²

or, h² = 289k²

or, h = 17

∴ sin θ = 8/17

Question 4 (x)

4 (x)Right Circular ConeEasy2 Marks

If the volume of a right circular cone is V cubic unit, the base area is A sq. unit and the height is H unit, then find the value of \frac{AH}{3V}

Answer

V = 1\over3πr²H

or, V = 1\over3AH   (∵ A = πr²)

or, 3 = \text{AH}\over \text{V}

or, \text{AH}\over \text{3V} = 1

Question 4 (xi)

4 (xi)Real Life Problems Related To Different Solid ObjectEasy2 Marks

Find the ratio of the volumes of a solid right circular cylinder and a solid right circular cone of equal radii and equal heights.

Answer

Volume of circular cylinder = πr²h

or, Volume of cone = 1\over 3πr²h

Ratio = Vcylinder : Vcone

= πr²h : 1\over 3πr²h

= 1 : 1\over 3 = 3 : 1

Question 4 (xii)

4 (xii)StatisticsEasy2 Marks

If 6, 8, 10, 12, 13, x are in increasing order and their mean and median are equal, then find the value of x.

Answer

Numbers in ascending order are 6, 8, 10, 12, 13, x

Mean = 6 + 8 + 10 + 12 + 13 + x\over 6 = 49 + x\over 6

No. of terms (n) (even)

Median = {\text{n}\over2} \text{term} +{\text{n}\over2} + 1 \text{term}\over 2 

= {6\over2} \text{term} +({6\over2} + 1) \text{term}\over 2 

= 3^{rd} \text{term} +4^{th} \text{term}\over 2 

= 10 + 12\over 2  = 11

ATP: Mean = Median

or, 49 + \text{x}\over 6 = 11

or, x = 17

Q

Question – 5

Answer any one questions: [5]

Question 5 (i)

5 (i)Compound InterestModerate5 Marks

The number of smokers is decreasing at the rate of 6 \frac{1}{4} % per year due to publicity of anti-smoking. If at present the number of smokers in a town is 22500, find the number of smokers of that town 2 years ago.

Answer

Amount (A) = ₹ 22500

Principal = P

Rate (r) = 61\over 4 %

time (n) = 2

A = P (1 – \text{r}\over 100)n

or, 22500 = P(1 – 25\over 4 × 100)2

or, 22500 = P(15\over 16)2

or, 22500 = P15\over 16 × 15\over 16

or, P =  22500 × 16\over 15 × 16\over 15

or, p = 25600

Thus, 2 years ago there were 25600 smokers.

Question 5 (ii)

5 (ii)PartnershipModerate5 Marks

In a partnership business, the ratio of the capital of three friends is 6: 4 : 3. After 4 months 1st friend withdraws his half of the capital and after 8 more months total profit is ₹ 61,050. Find the share of the profit of three friends.

Answer

Let the capital of A = 6x

Let the capital of B = 4x

Let the capital of C = 3x

Half of 6x = 3x

Ratio of capital with respect to 1 month:

= [(6x × 4) + (3x × 8)]: (4x × 12): (3x × 12)

= (24x + 24x): 48x: 36x

= 48x: 48x: 36x

= 4:4:3

Total profit = ₹ 61,050

Profit of A = Share of A × total profit

= 4\over 11 × 61050 = ₹ 22200

Profit of A = ₹ 22200

Similarly, Profit of B = ₹ 22200 (since the ratio of B is same as A)

Profit of C = 3 × 5550 = ₹ 16650

Q

Question – 6

Answer any one question : [3]

Question 6 (i)

6 (i)Quadratic Equation With One VariableModerate3 Marks

Solve: \frac{x-3}{x+3} – \frac{x+3}{x-3} + 6 \frac{6}{7} = 0

Answer

\text{x² – 6x + 9 – (x² + 6x + 9)}\over x² – 9 + 48\over 7 = 0

or, – \text{12x}\over \text{x² – 9} + 48\over 7 = 0

or, -84x + 48x² – 432 = 0

or, -7x + 4x² – 36 = 0

or, 4x² – 7x – 36 = 0

or, 4x² – (16x – 9x) – 36 = 0

or, 4x² – 16x + 9x – 36 = 0

or, 4x(x – 4) + 9(x – 4) = 0

or, (x – 4)(4x + 9) = 0

x = 4, -9/4

Question 6 (ii)

6 (ii)Quadratic Equation With One VariableModerate3 Marks

If the price of 1 dozen pens is reduced by ₹ 6, then 3 more pens will be got for ₹ 30. Calculate the price of 1 dozen pens before the reduction of price.

Answer

Let the price of 1 dozen pen at present is ₹ x

∴ In ₹ at present 12\over \text{x} × 30 pens = 360\over \text{x} pens are got

If the price is reduced by ₹ 6 per dozen, then it becomes ₹ (x – 6)

Then for Rs 30 we get 12\over \text{x – 6} × 30 pens = 360\over x – 6

As per question, 360\over \text{x – 6} – 360\over \text{x} = 3

or, 360(1\over \text{x – 6} – 1\over \text{x}) = 3

or, 120 {\text{x – x + 6}\over \text{(x – 6)x}} = 1

or, 120 {6\over \text{(x – 6)x}} = 1

or, 720\over \text{x² – 6x} = 1

or, x² – 6x – 720 = 0

or, x² – 6x – 720 = 0

or, x² – (30 – 24)x – 720 = 0

or, x² – 30x + 24x – 720 = 0

or, x(x – 30) + 24(x – 30) = 0

or, (x – 30)(x + 24) = 0

either x – 30 = 0 or x + 24 = 0

⇒ x = 30 or x = -24

But the price of pens cannot be negative, so x ≠ -24, hence x = 30

Hence, before the reduction of prices, the price of 1 dozen pens was Rs 30.

Q

Question – 7

Answer any one question: [3]

Question 7 (i)

7 (i)Quadratic SurdsModerate3 Marks

If x = \frac{1}{2-\sqrt{3}} and y = \frac{1}{2+ \sqrt{3} }, then find the value of \frac{1}{x+1} + \frac{1}{y+1}

Answer

x = \frac{1}{2-\sqrt{3}}

or, x + 1 = \frac{1}{2-\sqrt{3}} + 1

= \frac{1 + 2-\sqrt{3}}{2-\sqrt{3}}

= \frac{3 -\sqrt{3}}{2-\sqrt{3}} × \frac{2 +\sqrt{3}}{2 + \sqrt{3}}

= \frac{6 + 3\sqrt{3} – 2\sqrt{3} – 3}{4 – 3}

= 3 + √3

y = \frac{1}{2+\sqrt{3}}

y + 1 = \frac{1}{2+\sqrt{3}} + 1 = 3 – √3

Now, \frac{1}{x+1} + \frac{1}{y+1}

= \frac{1}{3 + √3} + \frac{1}{3 – √3}

= \frac{3 – √3 + 3 + √3}{9 – 3}

= \frac{6}{6} = 1

Question 7 (ii)

7 (ii)VariationHard3 Marks

If x ∝ y and y ∝ z, then show that \frac{x}{yz} + \frac{y}{zx} + \frac{z}{xy} ∝ \frac{1}{x} + \frac{1}{y} + \frac{1}{z}.

Answer

y ∝ z ⇒ y = k2z — (i)

x ∝ y ⇒ x = k1y ⇒x = k1k2z — (ii)

\frac{x}{yz} + \frac{y}{zx} + \frac{z}{xy} \propto \frac{1}{x} + \frac{1}{y} + \frac{1}{z}

or, \frac{\text{x² + y² + z²}}{xyz} ∝ \frac{\text{yz + xz + xy}}{\text{xyz}}

or, \frac{\text{x² + y² + z²}}{\text{yz + xz + xy}} = k

To prove the proportionality for the given expression, the value of \frac{\text{x² + y² + z²}}{\text{yz + xz + xy}} should be non-zero constant.

Now substitute the values of x and y from (i) and (ii),

{k_1}^2{k_2}^2z^2 + {k_2}^2 z^2 + z^2\over {k_1}{k_2}z({k_2}z) + k_2 z (z) + z (k_1k_2z)

= ({k_1}^2{k_2}^2 + {k_2}^2  + 1)z^2\over {k_1}{k_2}^2 + k_2  + (k_1k_2)z^2

= ({k_1}^2{k_2}^2 + {k_2}^2  + 1)\over {k_1}{k_2}^2 + k_2  + (k_1k_2)

= Non – zero constant

Q

Question – 8

Answer any one question: [3]

Question 8 (i)

8 (i)VariationModerate3 Marks

If \frac{\text{a²}}{\text{b+c}} =\frac{\text{b²}}{\text{c+a}} = \frac{\text{c²}}{\text{a+b}} = 1, then show that \frac{1}{\text{1+a}} + \frac{1}{\text{1+b}} + \frac{1}{\text{1+c}} = 1

Answer

\frac{\text{a²}}{\text{b + c}} = \frac{\text{b²}}{\text{c + a}} = \frac{\text{c²}}{\text{a + b}} = 1

∴ a2 = b + c ; b2 = c + a ; c2 = a + b

\frac{1}{\text{1 + a}} + \frac{1}{\text{1 + b}} + \frac{1}{\text{1 + c}}

= \frac{\text{a}}{\text{a + a²}} + \frac{\text{b}}{\text{b + b²}} + \frac{1}{\text{c + c²}}

= \frac{\text{a}}{\text{a + b + c}} + \frac{\text{b}}{\text{b + c + a}} + \frac{\text{c}}{\text{c + a + b}}

= \frac{\text{a + b + c}}{\text{a + b + c}} = 1 (Proved)

Question 8 (ii)

8 (ii)Ratio And ProportionModerate3 Marks

If the fourth and fifth of the five numbers in continued proportion are 54 and 162 respectively, find the first number.

Answer

Let the continued proportion be a, ak, ak², ak3, ak4

Given: ak3 = 54 — (1) and  ak4 = 162— (2)

Dividing (2) and (1)

k = 3

Put k in eq (1)

ak3 = 54

or, a × 33 = 54

or, a × 27 = 54

or, a = 2

So, first number will be ‘2′.

Q

Question – 9

Answer any one question: [5]

Question 9 (i)

9 (i)Theorems Related To Cyclic QuadrilateralModerate5 Marks

Prove that in a cyclic quadrilateral opposite angle are supplementary.

Answer

Given: ABCD is a cyclic quadrilateral

Prove that in a cyclic quadrilateral opposite angle are supplementary

To prove: ∠ABC + ∠ADC = 2 right angles and ∠BAD + ∠BCD = 2 right angles

Construction: Two diagonals AC and BD are drawn.

Proof: ∠ADB = ∠ACB [angles in the same segment of the circle]

Again, ∠BAC = ∠BDC [angles in the same segment of the circle]

Again, ∠ADC = ∠ADB + ∠BDC

= ∠ACB + ∠BAC

∴ ∠ADC + ∠ABC = ∠ACB + ∠BAC + ∠ABC

∴ ∠ADC + ∠ABC = 2 right angles [∴ sum of three angles of a triangle is 2 right angles]

Similarly we can prove that, ∠BAD + ∠BCD = 2 right angles

Question 9 (ii)

9 (ii)Theorem Related to a Tangent To a CircleModerate5 Marks

Prove that the tangent to a circle at any point on it is perpendicular to the radius that passes through the point of contact.

Answer

Given: AB is a tangent at the point P of a circle with center O and OP is a radius through the point P. To prove: OP and AB are perpendicular to each other i.e. OP ⊥ AB.

Prove that the tangent to a circle at any point on

Construction: Any other point Q is taken on the tangent AB, O, Q are joined.

Proof: Any other point on AB except P is outside the circle; ∴ OQ intersects the circle at a point. Let R be the point of intersection.

∴ OR < OQ [∴ R is a point between O, Q]

Again, OR = OP [∴ radii of the same circle]

∴ OP < OQ

∴ The point Q is any point on AB,

∴ OP is the least of all the line segments drawn from the center O to the tangent AB.

Again, the least distance is perpendicular distance.

∴ OP ⊥ AB (proved)

Q

Question – 10

Answer any one question: [3]

Question 10 (i)

10 (i)Theorems Related To Cyclic QuadrilateralModerate3 Marks

ABCD is a cyclic quadrilateral. Bisectors of ∠DAB and ∠BCD intersect the circle at X and Y respectively. If O be the centre of the circle, find ∠XOY.

Answer

Given:  The bisector of ∠DAB and ∠BCD intersect the circle at the points X and Y.

ABCD is a cyclic quadrilateral. Bisectors of ∠DAB and ∠BCD intersect the circle at X and Y respectively

To Find : ∠XOY

The angles ∠YAB and ∠YCB subtended by the minor arc YB are on the same segment of the circle.

∴ ∠YAB = ∠YCB = 1\over2 ZBCD —- (1) [ ∴ CY is bisector of ∠BCD]

Again, ∠XAY = ∠XAB + ∠YAB

= 1\over2 ∠BAD + 1\over2 ∠BCD [From (1) we get, ∴ AX is bisector of ∠DAB]

= 1\over2 (∠BAD + ∠BCD)

= 1\over2 × 180° [∴ ABCD is a cyclic quadrilateral]

= 90° ∴ ∠XAY is a semicircular angle.

∴ XY is a diameter and ∠XOY = 180°

Question 10 (ii)

10 (ii)Theorems Related To Cyclic QuadrilateralModerate3 Marks

Prove that a cyclic trapezium is an isosceles trapezium.

Answer

Prove that a cyclic trapezium is an isosceles trapezium

ABCD is a cyclic trapezium of which AD || BC

AB = DC or ABCD is a rectangle and AC = BD.

∠ADC + ∠DCB = 180° [∠ AD || BC and DC is transversal]

Again, ∠BAD + ∠DCB = 180° [∠ ABCD is a cyclic quadrilateral]

∴ ∠ADC + ∠DCB = ∠BAD + ∠DCB ∴ ∠ADC = ∠BAD ..

In ∆BAD and ∆ADC, ∠BAD = ∠ADC [From (1) we get]

∠ABD = ∠DCA [∴ Angles in the same segment]

AD is common side

∴ ∆BAD = ∆ADC [A-A-S congruence property]

∴ AB = DC .. ABCD is an isosceles trapezium or a rectangle and AC = BD (Similar part of congruent triangle) [Proved]

Q

Question – 11

Answer any one question: [5]

Question 11 (i)

11 (i)Construction of Circumcircle and IncircleModerate5 Marks

Draw a right-angled triangle of which two sides containing the right angle have the lengths 5 cm and 6 cm. Now draw an incircle of the triangle.

Answer

Draw a right angled triangle of which two sides containing the right angle have the lengths

Steps of construction:

  1. Draw a line BC of 6 cm.
  2. At point B draw a right angle.
  3. Take a distance of 5 cm and cut an arc from the point B. This will give the point
  4. Join A to C. This is the right angle triangle ABC.
  5. Draw angle bisector of any two angles say ∠B and ∠C of △ABC and let these intersect at a point say O.
  6. Taking O as centre and OM as radius, draw a circle.
  7. The circle touches the other two sides of triangle. This will be the required in circle of the triangle.

Question 11 (ii)

11 (ii)Determination of Mean ProportionalModerate5 Marks

Construct a square of the equal area of ​​an equilateral triangle of side 7 cm.

Q

Question – 12

Answer any two questions: [3 × 2 = 6]

Question 12 (i)

12 (i)Trigonometric Ratios And Trigonometric IdentitiesModerate3 Marks

If cos θ = \frac{x}{\sqrt{x²+y²}} , then prove that x sin θ = y cos θ

Answer

Cos θ = \text{x}\over \sqrt{\text{x² + y²}}

base (b) = x

hypotenuse (h) = \sqrt{\text{x² + y²}}

Pythagoras Theorem:  p² = h² – b²

or, p² = x² + y² – x²

or, p² = y²

or, p = y

LHS: x sin θ = x \text{y}\over \sqrt{\text{x² + y²}}

= y \text{x}\over \sqrt{\text{x² + y²}}

= y cos θ RHS 

Hence, x sin θ = y cos θ proved

Question 12 (ii)

12 (ii)Concept of Measurement of AngleEasy3 Marks

Radius of a circle is 7 cm. Find the angle in radians which is subtended by an arc of this circle of length 5.5 cm at the centre of the circle.

Answer

Length of arc = 5.5 cm

Radius of the circle = 7 cm

Angle substend by arc (θ) = 5.5\over 7 = 11\over 14 radians

or, Angle substended by arc at the centre

= 11\over 14 × 180\over π

= 11\over 14 × 180 × 7\over 22

= 45º or π/4

Question 12 (iii)

12 (iii)Trigonometric Ratios And Trigonometric IdentitiesModerate3 Marks

Show that \text{tan θ + sec θ – 1}\over \text{tan θ – sec θ + 1} = 1 + \text{sin θ}\over \text{cos θ}

Answer

LHS: \text{tan θ + sec θ – 1}\over \text{tan θ – sec θ + 1}

= \text{(tan θ + sec θ) – (sec² θ – tan² θ)}\over \text{tan θ – sec θ + 1}

= \text{(sec θ + tan θ) – (sec θ + tan θ)(sec θ – tan θ)}\over \text{tan θ – sec θ + 1}

= \text{(sec θ + tan θ)(1 – sec θ + tan θ)}\over \text{tan θ – sec θ + 1}

= sec θ + tan θ

= 1\over \text{cos θ} + \text{sin θ}\over \text{cos θ}

= 1 + \text{sin θ}\over \text{cos θ}

Q

Question – 13

Answer any one question: [5]

Question 13 (i)

13 (i)Application of Trigonometric RatiosModerate5 Marks

Angle of elevation of the top of an incomplete tower from a point at a distance 50 m from its foot is 30°. How much should the height of the tower be increased so that the angle of elevation of the top will be 45° from that point?

Answer

Angle of elevation of the top of an incomplete tower from a point at a distance 50 m from its foot is 30°

In ΔABO

tan 30° = \text{AB}\over \text{OA}

or, 1\over √3 = \text{AB}\over 50

or, AB = 50\over √3 = 28.86 m

In ΔAOC,

tan 45° = \text{AC}\over \text{OA}

or, AC = 50 m

Height of the of tower increased = 50 m – 28.86 m

= 21.13 m

Question 13 (ii)

13 (ii)Application of Trigonometric RatiosModerate5 Marks

From the roof of the building the angle of depression of the top and foot of the lamp post is 30° and 60° respectively. Find the ratio of the heights of the building and the lamp post.

Answer

From the roof of the building the angle of depression of the top and foot of the lamp post is 30° and 60° respectively

In ΔEDC, tan 30° = \text{ED}\over \text{DC}

or, 1\over √3 = \text{AE – AD}\over \text{CD} — (1)

In ΔEAB,

tan 60° = \text{AE}\over \text{AB}

or, √3 = \text{AE}\over \text{CD} — (2)

Divide (1) by (2),

\text{AE – AD}\over \text{AE} = 1\over √3 × 1\over √3

or, {\text{AE}\over \text{AE}} – {\text{AD}\over \text{AE}} = 1\over 3

or, 1 – {\text{AD}\over \text{AE}} = 1\over 3

or, {\text{AD}\over \text{AE}} = 1 – 1\over 3

or, {\text{AD}\over \text{AE}} = 2\over 3

or, {\text{BC}\over \text{AE}} = 2\over 3

or, {\text{AE}\over \text{BC}} = 2\over 3

The ratio of the heights of building and lamp post = 3 : 2

Q

Question – 14

Answer any two questions: [4 × 2 = 8]

Question 14 (i)

14 (i)SphereModerate4 Marks

Two solid spheres with radii of 1 cm and 6 cm lengths are melted and a hollow sphere with an outer radius of 9 cm is made. Determine the inner radius of the new hollow sphere.

Answer

Volume of sphere = 4\over3πr³

Total volume of two sphere = 4\over3π(1³ + 6³)

Let internal radius of hollow sphere = r cm

Volume of the iron of this sphere = 4\over3π(9³ – r³)

According to the question,

4\over3π(1³ + 6³) = 4\over3π(9³ – r³)

or, (1³ + 6³) = (9³ – r³)

or, r³ = 9³ – 1³ – 6³ = 512

or, r³ = 8³

or, r = 8 cm

Question 14 (ii)

14 (ii)Right Circular ConeModerate4 Marks

The height of a right circular cone is twice the radius of the base. If the height were seven times the diameter of the base then the volume of the cone would have been 539 cu cm more. Find the height of the cone.

Answer

Let, radius of cylinder = r and the height of cylinder = 2r

If its height be 7 times its diameter, new height of cylinder = 14r

Case – 1: Volume = 1\over 3 2πr²h

= 1\over 3 × 2 × 22\over 7 × r² × 2r

= 44r³\over 21

Case – 2:  Radius = r, Height = 14r

Volume = 1\over 3 πr²h

= 1\over 3 × 2 × 22\over 7 × r² × 14r

= 308r³\over 21

According to the Question,

14\over 3 × πr³ – 2\over 3 × πr³ = 539

or, 4πr³ = 539

or, 4 × 22\over 7 × r³ = 539

or, r³ = 539 × 7\over 22 × 4

or, r³ = 7 × 7 × 7 \over 2 × 2 × 2

or, r = 7\over 2 = 3.5 cm

Given Height is twice of the radius,

H = r × 2 = 3.5 × 2 = 7 cm

Question 14 (iii)

14 (iii)Right Circular CylinderModerate4 Marks

The curved surface area of ​​a right circular cylindrical wooden log of uniform density is 440 sq. decimeters. The weight of 1 cubic decimeter of wood is 3 kg and the weight of a log is 18.48 quintals. Find the diameter of the log.

Answer

Given:

  • Curved surface area = 440 sq. decimeters
  • Density of the wood = 3 kg per cubic decimeter
  • Weight of the log = 18.48 quintals (1 quintal = 100 kg)

Convert the weight of the log to kilograms:

Weight of the log = 18.48 × 100 = 1848 kg

Formula for the curved surface area (CSA) of a cylinder:

CSA = 2πrh

Given that CSA = 440:

2πrh = 440 — (1)

Volume of the cylinder:

Volume = πr²h

Weight of the log = Volume × Density

1848 = πr²h × 3

πr²h = 616 — (2)

Divide the second equation by the first:

πr²h \over 2πrh = 616 \over 440

r \over 2 = 14 \over 10

r = 2.8 decimeters

Diameter = 2r = 2 × 2.8 = 5.6 decimeters

Therefore, the diameter of the log is 5.6 decimeters.

Q

Question – 15

Answer any two questions: [4 × 2 = 8]

Question 15 (i)

15 (i)StatisticsModerate4 Marks

If the arithmetic mean and total frequency of the following distribution are 50 and 120 respectively, then find the value of f1 and f2:

Class Frequency
0 – 20 17
20 – 40 f1
40 – 60 32
60 – 80 f2
80 – 100 19
Answer
Class x f fx
0 – 20 10 17 170
20 – 40 30 f1 30f1
40 – 60 50 32 1600
60 – 80 70 f2 70f2
80 – 100 90 19 1710
Total 68 + f1 + f2 3480 + 30f1 + 70f2

Σf = 120

or, 68 + f1 + f2 = 120

or, f1 + f2 = 120 – 68

or, f1 + f2 = 52 — (1)

Σfx = mean × Σf

or, 3480 + 30f1 + 70f2 = 50 × 120

or, 30f1 + 70f2 = 2520

or, 3f1 + 7f2 = 252 — (2)

Solving (1) and (2), we get

f1 = 28

and  f2 = 24

Hence, the values of f1 and f2 are 28 and 24.

Question 15 (ii)

15 (ii)StatisticsEasy4 Marks

Construct the table of cumulative frequency (greater than type) and draw the ogive from the following frequency distribution :

Class Frequency
0 – 10 7
10 – 20 10
20 – 30 23
30 – 40 50
40 – 50 6
50 – 60 4
Answer
Class Cummulative Frequency
Greater than 0 100
Greater than 10 93
Greater than 20 83
Greater than 30 60
Greater than 40 10
Greater than 50 4
Greater than 60 0

Construct the table of cumulative frequency (greater than type) and draw the ogive from the following frequency distribution

Question 15 (iii)

15 (iii)StatisticsModerate4 Marks

Find the mode of the following frequency distribution :

Class Frequency
50 – 59 5
60 – 69 20
70 – 79 40
80 – 89 50
90 – 99 30
100 – 109 6
Answer
Class Class boundary Frequency
50 – 59 49.5 – 59.5 5
60 – 69 59.5 – 69.5 20
70 – 79 69.5 – 79.5 40
80 – 89 79.5 – 89.5 50
90 – 99 89.5 – 99.5 30
100 – 109 99.5 – 109.5 6

Modal class = 79.5 – 89.5

  • = 79.5
  • =  50
  • = 40
  • = 30
  • =  10

Mode = 79.5 + (50 – 40\over 2×50 – 40 – 30) × 10

= 79.5 + (10\over 30) × 10

= 79.5 + (100\over 30)

= 82.833

Q

Question – 11 (B)

[Alternative Question for Sightless Candidates]

Question 11 (i)

11 (i)Construction of Circumcircle and IncircleEasy5 Marks

Describe the process of drawing an incircle of a right-angled triangle.

Answer

The process of drawing an incircle of a right-angled triangle

  1. Make a right-angled triangle (one angle should be 90°).
  2. Cut two angles of the triangle into half using a compass (for example, angle at A and angle at C).
  3. The two bisectors will meet at a point inside the triangle. This point is called the incenter.
  4. From the incenter, draw a straight line to one side of the triangle so that it meets the side at 90°. The length of this line is the radius of the circle.
  5. Place the compass on the incenter, set its length equal to the radius, and draw a circle.

Question 11 (ii)

11 (ii)Determination of Mean ProportionalModerate5 Marks

Describe the method of construction of a square of the equal area of ​​an equilateral triangle.

Answer

Construction Procedure:

(i) I drew a triangle ABC, of which AB, BC, and CA are 7 cm, 6 cm, and 3 cm, respectively.

(ii) I drew a rectangle EFCG whose area is equal to the area of triangle ABC.

(iii) Now from the extended EG, I cut off GK, which is equal to GC.

(iv) Now I drew a semicircle by taking the line segment EK as the diameter.

(v) I extended CG, which intersects the semicircle at the point.

(vi) I drew a squared figure HGJI by taking the side GH.

HGJI is the required square whose area is equal to the area of triangle ABC.

Q

Question -16 (a) · External Candidates

Answer any three questions: [2 × 3 = 6]

Question 16 (a.i)

16 (a.i)VariationModerate2 Marks

If x ∝ y, y ∝ z and z ∝ x, then find the relation between the constants of variations.

Answer

x ∝ y implies x = k1 y.

y ∝ z implies y = k2 z.

z ∝ x implies z = k3 x.

Substitute y = k2 z into x = k1 y:

x = k1 (k2 z) = k1 k2 z.

Now substitute x = k1 k2 z into z = k3 x:

z = k3 (k1 k2 z).

Simplifying:

z = k1 k2 k3 z.

For this to hold true, k1 k2 k3 = 1.

Thus, the relation between the constants is:

k1 k2 k3 = 1.

Question 16 (a.ii)

16 (a.ii)PartnershipEasy2 Marks

In a partnership business, the capital of A is 1\frac{1}{2} times that of B. At the end of the year if B gets ₹ 1,500 as a share of the profit, find the share of A.

Answer

Capiatal ratio of A and B = \frac{3}{2} : 1 = 3 : 2

Sum of ratio = 3 + 2= 5

Profit share of B = ₹ 1500

Let P be the total profit

or, \frac{2}{5} × P = ₹ 1500

or, P = ₹ 1500 × \frac{5}{2} = ₹ 3750

Profit share of A = \frac{3}{5} × 3750 = ₹ 2250

Question 16 (a.iii)

16 (a.iii)Quadratic SurdsModerate2 Marks

If x + √(x² – 9) = 9 then find the value of x – √(x² – 9).

Answer

x + √(x² – 9) = 9

or, 9 – x = √(x² – 9)

squaring both sides

(9 – x)² = {√(x² – 9)}²

or, 81 – 18x + x² = x² – 9

or, 81 – 18x = – 9

or, 18x = 90

or, x = 5

Now, x – √(x² – 9) =  5 – √(5² – 9)

= 5 – √16

= 5 – 4 = 1

Question 16 (a.iv)

16 (a.iv)SphereModerate2 Marks

The numerical value of the volume of a sphere is twice the numerical value of its surface area. Find the radius of the sphere.

Answer

Volume of the sphere = 4\over3πr³

Surface area of the sphere = 4πr²

Given that the volume is twice the surface area:

⇒ 4\over3πr³ = 2 × 4πr²

⇒ 4\over3r³ = 8r²

⇒ 4\over3r = 8

⇒ 4r = 24

⇒ r = 6

Thus, the radius of the sphere is 6 units.

Q

Question -16 (b) · External Candidates

Answer any four questions: [1 × 4 = 4]

Question 16 (b.i)

16 (b.i)Quadratic SurdsModerate1 Mark

Which one is greater √7 – √2 or √8 – √3?

Answer

x = √7 – √2

1\over \text{x} = 1\over √7 – √2

= √7 + √2\over 5

y = √8 – √3

1\over \text{y} = 1\over √8 – √3

= √8 + √3\over 5

Clearly, 1\over \text{x} > 1\over \text{y}

or, y > x

or, √8 – √3 > √7 – √2

Question 16 (b.ii)

16 (b.ii)Quadratic Equation With One VariableEasy1 Mark

Under which condition the quadratic equation ax2 + bx + c = 0 (a ≠ 0) have one zero roots.

Answer

The condition for the quadratic equation ax² + bx + c = 0 to have one zero root is:

b ≠ 0 and c = 0.

Question 16 (b.iii)

16 (b.iii)SimilarityEasy1 Mark

If the lengths of three sides of two triangles are in proportion, then which type of triangle is this?

Answer

If the lengths of the corresponding sides of two triangles are in proportion, then the two triangles are similar triangles.

Question 16 (b.iv)

16 (b.iv)Simple InterestEasy1 Mark

In how many years a sum of money at 6 \frac{1}{4}% simple interest per annum would be 4 double?

Answer

Principal = P

rate = 6 \frac{1}{4}% = \frac{25}{4}%

Amount = 4P

Simple Interest (SI) = 4P – P = 3P

Time (t) = \frac{SI × 100}{\text {P × r}}

or, Time (t) = \frac{3p × 100}{\text {P × 25/4}} = 16 years

Question 16 (b.v)

16 (b.v)Theorem Related To Angle In A CircleEasy1 Mark

Fill up the blank : The front angle formed at the center of a circle by an arc is the ____ of the angle formed by the same arc at any point on the circle.

Answer

The front angle formed at the center of a circle by an arc is twice the angle formed by the same arc at any point on the circle.