Question

Упростить выражение : sin^2a+sin^2a×ctg^2a

Answer 1

$sin^2 alpha +sin^2 alpha *ctg^2 alpha =sin^2 alpha (1+ctg^2 alpha )=sin^2 alpha * frac{1}{sin^2 alpha }=1$
$1+ctg^2 alpha = frac{1}{sin^2 alpha }$