Question

найдите значение выражения

Answer 1

$frac{6}{sin(frac{11pi}{4})*cos(-frac{9pi}{4})}=frac{6}{sin(frac{pi}{2}+frac{9pi}{4})*cos(frac{9pi}{4})}=frac{6}{sin(frac{pi}{2}+frac{9pi}{4})*cos(frac{9pi}{4})}=\=frac{6}{cos(frac{9pi}{4})*cos(frac{9pi}{4})}=frac{6}{cos^2(frac{9pi}{4})}=6*2=12$