Question

cos(3pi/2-2a)/1+cos2a*ctg(pi+a) упростите

Answer 1

$\frac{cos (\frac{3 \pi }{2} -2 \alpha )}{1+cos2 \alpha } ctg( \pi + \alpha )=$ $=\frac{-sin2 \alpha }{cos ^{2} \alpha +sin ^{2} \alpha +cos ^{2} \alpha -sin ^{2} \alpha } ctg \alpha = \frac{-2cos \alpha sin \alpha }{2cos ^{2} \alpha } * \frac{cos \alpha }{sin \alpha } =-1$