Question

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

Answer 1

Given, 

sin 3A = cos (A – 26°) 

Using cos (90 – θ) = sin θ, we have 

sin 3A = sin (90° – (A – 26°)) 

Now, comparing both L.H.S and R.H.S 

3A = 90° – (A – 26°) 

3A + (A – 26°) = 90° 

4A – 26° = 90° 

4A = 116° 

A = \(\frac{116°}{4 }\)

∴ A = 29°