Sin7π/24cosπ\8-cos7π/24sinπ/8 помогите

Question

Sin7π/24cosπ\8-cos7π/24sinπ/8 помогите

Answer 1

7π/24=α   π/8=β    sinαcosβ-cosαsinβ=sin(α-β)
выражение равно   sin(7π/24-π/8)=sin(4π/24)=sin(π/6)=1/2