Ex 8.1, 6 - If A and B are acute angles, cos A = cos B, then show that A = B.

  1. Chapter 8 Class 10 Introduction to Trignometry
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Ex 8.1, 6 If ∠ A and ∠ B are acute angles such that cos A = cos B, then show that ∠ A = ∠ B. cos A = (Side adjacent of angle A) / Hypotenuse = AC/AB Similarly, cos B = (Side adjacent of angle A) / Hypotenuse = BC/AB Now it is given that cos A = cos B AC/AB = BC/AB AC = BC We know that in a triangle, angles opposite equal sides are equal ∠B = ∠A Hence proved.

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