2cos^2x等于cos^4x么?
cos^4(x)-sin^4(x)等于?是cos^2(x)还是cos2x
(1+cos x/2)/2等于多少?
(tanx+1/tanx)cos^2 x等于
y=sin^2x-3sinxcosx+4cos^2x是否等于y=sin^2x+cos^2x+3cos^2x-3/2*si
cos(x^2)dx
cos x>-1/2
1-2cos^2 x/4为什么等于-cosx/2
∫X^2COS^2(X/2)dx等于多少?
sec 2x等于cos 2x 分之一吗
sin^2(x)cos^2(x)积分等于多少
cos^2x-sin^2x等于多少?
[sin^2(x)-cos^2(x)] 为什么等于-cos2x