Question

решить (2 sin (A-7П)+cos(3П/2)+A))/sin(A+П)

Answer 1

$\dfrac{2sin(a-7 \pi )+cos( \frac{3 \pi }{2}+a) }{sin(a+ \pi )}=\dfrac{-2sin(\pi-a )+sina }{-sina}= \\ =\dfrac{-2sina+sina }{-sina}= \dfrac{-sina}{-sina}=1.$