1) 4cos a/4 cos 2n+a/2 2) 1/ 1-tga - 1/1+tga 3) (sina/1+cosa + sina/1-cosa) sin2a...

Question

1) 4cos a/4 cos 2n+a/2
2) 1/ 1-tga - 1/1+tga
3) (sina/1+cosa + sina/1-cosa) sin2a
Упростите

Answer 1

1/ (1-tga )- 1/(1+tga)=(1+yga-1+tga)/(1-tg²a)=2tga/(1-tg²a)=tg2a

(sina/1+cosa + sina/1-cosa) sin2a=[sina(1-cosa+1+cosa)]*sin2a/(1-cos²a)=
=2sina*2sinacosa/sin²a=4cosa