Question

упростить срочно очень!!!
1) 1-2sin^2a+cos2a; 2) 1-cos2a/sin^2a; 3) 2cos2a*tga/1-tg^2a
тожденство
sina*cosa-tga/1-(sina+cosa)^2=1/2tg^2a

Answer 1

1)=cos2a+cos2a=2cos2a
2)=2sin²a/sin²a=2
3)=(sina*cos²a-sina)/cosa : (sin²a+cos²a-sin²a-2sinacosa-cos²a)=
=sina(cos²a-1)/cosa : (-2sinacosa)=-sin³a/cosa*1/(-2sinacosa)=sin²a/2cos²a=
=1/2*tg²a