A hint to get started
Prove a fourth-power trigonometric identity
Show that .
CJC · Discussion · Question 14
Start from the right-hand side, replace cos 2θ, then replace cos θ using the half-angle identity.
Read the worked solution
A hint to get started
Show that sin4(θ/2)≡81(3−4cosθ+cos2θ).
CJC · Discussion · Question 14
Start from the right-hand side, replace cos 2θ, then replace cos θ using the half-angle identity.