In Exercises 39-42

MATHEMATICS · Subjective · AP · AP Precalculus · Trigonometric and Polar Functions · Trigonometric and Polar Functions

Problem

In Exercises 39-42, use the power-reducing identities to prove the identity. 39. `

\sin ^{4} x=\frac{1}{8}(3-4 \cos 2 x+\cos 4 x)