2(cos x)^2=1+cos 2x,
∫ (1+cos^2 x)/cos^2 x dx =
Cos x=-1/2
cos x=1/2,求x?
cos x>-1/2
已知f(x)=sin(x/2) + cos(x/2) +[cos(x/2)]^2-1/2
化简f(x)=2cos(x/2)·(sin(x/2)+cos(x/2))-1
已知函数f(x)=2Cos x(Sin x-Cos x)+1
Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y)
cos^2 x=(cos2x-1)/2
微积分1/cos^2(x)dx=?
2cos x (sin x -cos x)+1