Question

$frac{2cos(frac{3 pi }{2} ) - sin(- frac{3}{2} + beta )}{ 5cos( beta - pi )}$

Answer 1

$frac{2cos frac{3 pi }{2}-sin(- frac{ 3pi }{2}+ beta ) }{5cos( beta - pi )} = frac{2*0-sin(-( frac{ 3pi }{2}- beta ))}{5*cos(-( pi - beta ))} = frac{-(-sin( frac{ pi }{2}- beta ))}{5*cos( pi - beta )} = frac{cos beta }{-5cos beta }$
$=- frac{1}{5}=-0,2$

Answer 2

Сверху не sin(Пи/2+B), а sin(3/2+B)