Question

Найти значение выражения
$sqrt{32} cos^{2} frac{13 pi }{8} - sqrt{32} sin^{2} frac{13 pi }{8}$

Answer 1

√32cos²13π/8-√32sin²13π/8=√32·(cos²13π/8-sin²13π/8)=
=√32·cos13π/4=√32·cos(2π+π+π/4)=
=-√32·cosπ/4=-4√2·√2/2=-4