Упростить выражения:

1.

2.

1) 1 / (1+ctgx) - 1 / (1-ctgx) = (1-ctgx-1-ctgx) / (1-ctg²x) = - 2ctgx / (1-ctg²x) =

=-2cosx/sinx : (sin²x-cos²x) / sin²x=2cosx/sinx*sin²x / (cos²x-sin²x) = sin2x/cos2x=tg2x

2) 1 / (1-tgx) - 1 / (1+tgx) = (1+tgx-1+tgx) / (1-tg²x) = 2tgx / (1-tg²x) = tg2x