Упростите выражения
а)(sin x - cos x)^2/(sin2x-1)
б) 2sin a + (2cos^2 a)/(1+sin a)

а)=(sin^2(x) - 2sinx*cosx+cos^2(x))(sin2x-1) = (1-sin2x)(sin2x-1) = -1
б)=(2sina+2sin^2(a)+2cos^2(a))(1+sina) = (2sina+2)(1+sina) = 2