WBBSEClass XMathematicsTrigonometric Ratios And Trigonometric Identities01 Mark2024 Moderate

QQuestion

The minimum value of tanθ + cotθ is

(a) 0

(c) -2

(b) 2

(d) 1

Exam-ready answer 01 Mark

Answer

(b) 2

Explanation:

tanθ + cotθ

= (sinθ/cosθ) + (cosθ/sinθ)

= (sin²θ + cos²θ) / (sinθ cosθ)

= 1 / (sinθ cosθ)

Now, we know sin2θ = 2 sinθ cosθ

⇒ sinθ cosθ = (1/2) sin2θ

So, tanθ + cotθ = 1 / (sinθ cosθ) = 2 / sin2θ

The maximum value of sin2θ = 1

So, minimum value of 2 / sin2θ = 2 / 1 = 2

Therefore, minimum value = 2.

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