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WBBSEClass 10MathematicsTheorems Related To Cyclic Quadrilateral05 Mark2023 Moderate

QQuestion

Prove that in a cyclic quadrilateral opposite angle are supplementary.

Exam-ready answer • 05 Mark

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

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