Question

sin^2x/2-cos^2x/2 при x=2п/3
Помогите срочно

Answer 1

при x=2п/3:

$sin^2 (frac{x}{2})-cos^2 (frac{x}{2})=-cos (2*frac{x}{2})=-cos x=-cos frac{2*pi}{3}=cos frac{pi}{3}=frac{1}{2}$