Question

Срочно, Тригонометрия, 10 кд​

Answer 1

$cos^2 frac{pi}{8}+sin frac{pi}{8} cdot cos frac{3pi}{8} =$

$cos^2 frac{pi}{8}+sin frac{pi}{8} cdot cosleft( frac{pi}{2}- frac{pi}{8} right) =$

$cos^2 frac{pi}{8}+sin frac{pi}{8} cdot sin frac{pi}{8} right) =$

$cos^2 frac{pi}{8}+sin^2 frac{pi}{8}=1$

Ответ: 1