Prove that, ( A + B)^2 + ( A + B)^2 = 4 ^2 A-B 2 .

MATHEMATICS · Subjective · CBSE · Mathematics · Trigonometric Functions · Trigonometric Functions

Problem

Prove that,

(\cos A + \cos B)^2 + (\sin A + \sin B)^2 = 4 \cos^2 \frac{A-B}{2}.