Question

найдите 16/cos^2 37+1+cos^2 53

Answer 1

$frac{16}{cos^237+1+cos^253} =[; cosa=sin(90-a); ]= frac{16}{sin^2(90-37)+1+cos^253} =\\= frac{16}{underbrace {sin^253+cos^253}_{1}+1} = frac{16}{1+1} = frac{16}{2}=8$