Упростите выражение:

1) sinX*cosX*tgX

2) sin^2t - cos^2t/ctg (-t) tgt

3) cos2X-sin^2x/2sin^2x-cos^2x

1) sinx*cosx * (sinx/cosx) = sin^2 (x)

2) (sin^2 (t) - cos^2 (t)) / (cost*sint/sint*cost) = sin^2 (t) - cos^2 (t) = - (cos^2 (t) - sin^2 (t)) = - cos (2t)

3) (cos (2x) - sin^2 (x)) / (2sin^2 (x) - cos^2 (x)) = (cos^2 (x) - sin^2 (x) - sin^2 (x)) / (2sin^2 (x) - cos^2 (x)) = (cos^2 (x) - 2sin^2 (x)) / (2sin^2 (x) - cos^2 (x)) = - 1