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Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 9

Find all the angles of the given cyclic quadrilateral ABCD in the figure.

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Question

Find all the angles of the given cyclic quadrilateral ABCD in the figure.

Sum
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Solution

In a cyclic quadrilateral ABCD,

∠B + ∠D = 180°  ...(Sum of the opposite angles of a cyclic quadrilateral is 180°)

6x – 4° + 7x + 2° = 180°

13x – 2° = 180°

13x = 182°

x = 182°

x = `(182^circ)/13`

x = 14°

∠B = 6x – 4°

= 6(14) – 4°

= 84 – 4

= 80°

∠D = 7x + 2°

= 7(14) + 2°

= 98 + 2

= 100°

2y + 4° + 4y – 4° = 180° ...(Sum of the opposite angles of a cyclic quadrilateral is 180°)

6y = 180°

y = `(180^circ)/6`

= 30°

∠A = 2y + 4°

= 2(30) + 4°

= 64°

∠C = 4y – 4°

= 4(30) – 4°

= 120° – 4°

= 116°

∴ ∠A = 64°, ∠B = 80°, ∠C = 116°, ∠D = 100°.

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Chapter 4: Geometry - Exercise 4.4 [Page 173]

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Samacheer Kalvi Mathematics [English] Class 9 TN Board
Chapter 4 Geometry
Exercise 4.4 | Q 3 | Page 173

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