Question

10 кл.
Упростите выражение

Answer 1

$frac{cos( pi - alpha )+cos( frac{3 pi }{2} + alpha )}{1+2cos(- alpha )*sin(- alpha )} =frac{-cos alpha+sin alpha }{1-2cosalpha *sin alpha } =frac{sin alpha-cos alpha }{cos^2 alpha +sin^2 alpha -2cosalpha *sin alpha }=$$=frac{sin alpha-cos alpha }{(sin alpha -cos alpha)^2 } = frac{1}{sin alpha -cos alpha}$