Question

На помощь, товарищи!
$frac{1-cos alpha }{sin^{2} alpha }$

Answer 1

$frac{1-cosx}{ sin^{2} x} = frac{1-cosx}{1- cos^{2} x}= frac{1-cosx}{(1-cosx)*(1+cosx)} = frac{1}{1+cosx}$