Упростить 1. 19 cos^2 x — 9+19 sin^2 x 2. 17 cos^2 x — 5+17 sin^2 x 3. (sin^3 x — cos^3 x) / (1+sinxcosx)+cosx — sinx

1. 19 cos^2 x — 9+19 sin^2 x=19 (cos^2 (x)+sin^2 (x) -9=19-9=102. 17 cos^2 x — 5+17 sin^2 x=17 (cos^2 (x)+sin^2 (x) -5=17-5=123. (sin^3 x — cos^3 x) / (1+sinxcosx)+cosx — sinx=[ (sinx-cosx) (sin^2 (x)+sinxcosx+cos^2 (x) / (1+sinxcosx) ]+cosx-sinx=[ (sinx-cosx) (1+sinxcosx) ]/ (1+sinxcosx) ]+cosx-sinx=sinx-cosx+cosx-sinx=0