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In ∆PQR, ∠P = 70° and ∠R = 30°. Which side of this triangle is the longest? Give reason for your answer.

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Question

In ∆PQR, ∠P = 70° and ∠R = 30°. Which side of this triangle is the longest? Give reason for your answer.

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Solution

Given, in ΔPQR, ∠P = 70° and ∠R = 30°.

We know that, sum of all the angles of a triangle is 180°.

∠P + ∠Q + ∠R = 180°

∴ ∠Q = 180° – (70° + 30°)

= 80°

We know that here ∠Q is longest, so side PR is longest  ...[∴ Since in a triangle, the side opposite to the largest angle is the longest]

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Chapter 7: Triangles - Exercise 7.2 [Page 65]

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NCERT Exemplar Mathematics Exemplar [English] Class 9
Chapter 7 Triangles
Exercise 7.2 | Q 8. | Page 65

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