Question

If cos 2θ = sin 4θ where 2θ, 4θ are acute angles, find the value of θ.

Answer 1

We know that sin (90 - θ) = cos θ

sin 20 = cos 2θ

sin 4θ = sin (90 - 2θ)

4θ = 90 – 20

6θ = 90

`θ = 90/6`

θ = 15°