Question

If sin 3 A = cos (A − 26°), where 3 A is an acute angle, find the value of A.

Answer 1

sin 3 A = cos (A − 26°) (given)

or cos (90° – 3A) = cos (A – 26°)

On comparing

90° – 3A = A – 26°

A + 3A = 90° + 26°

4A = 116° = 29°

The value of A is 29°.