Question

Вычисли: sin π 5 ⋅ cos 2 π 15 + cos π 5 ⋅ sin 2 π 15

Answer 1

$sin(apm b)=sinacosbpm cosasinb\\sinfrac{pi}{5}* cosfrac{2pi}{15}+cosfrac{pi}{5} sinfrac{2pi}{15}=sin(frac{pi}{5}+frac{2pi}{15})=sinfrac{pi}{3}=frac{sqrt3}{2}.$