Prove that root 2 + root 2 + 2cos4 theta = 2 cos theta - Maths - Trigonometric Functions

Question

Prove that root 2 + root 2 + 2cos4 theta = 2 cos theta

Anuradha Sharma · Accepted Answer

2+2+2cos4θ=2+2+22cos22θ-1=2+2+4cos22θ-2=2+22cos22θ=2+2cos2θ=2+22cos2θ-1=2cosθ