669. Упростите выражение: a) (sin(alpha - pi) * cos(pi/2 + alpha))/(sin(pi/2 + alpha) * cos(2pi - alpha)) 8) (cos(pi - alpha) * sin((3pi)/2 - alpha))/(sin(pi + alpha) * cos(2pi - alpha)) 6) (2 - 2sin^2 (pi + alpha))/(sin(pi/2 + alpha) - cos(pi - alpha)) г) cos^ prime (2pi - alpha) + sin^3 ((3pi)/2 - alpha) tg|( pi 2 + alpha)sig^ prime ( 3 pi 2 + alpha) ,