Question

Упростите выражения: 1) sin^2 x - 1 2) sin2x/cosx 3)2ctgx * sinx - cosx 4) cos^2 x - 1

Answer 1

1)-(1-sin^2 x)= - cos^2 x.
2) (2sin x * cos x)/cos x= 2 sin x
3)2cosx/sin x* sin x - cos x= 2 cos x- cos x = cos x.
4) -(1-cos^2x)= - sin^2 x