化简cos^4(a/2)-sin^4(a/2)
化简 1-sin^4a-cos^4a/cos^2a-cos^4a
化简(1-sin^6 a-cos^6 a)/(cos^2 a-cos^4 a)==
化简cos^4(a/2)-sin^4(a/2)=
Sin^4a+Sina*Cosa+Cos^2a化简
证明sin(4A)sin(2A)(1-cos(2A)) cos(4A)cos(2A)(1 cos(2A))=cos(2A
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a
(cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=?
(1-sin^6a-cos^6a)/(sin^2a-sin^4a)
急.三角函数:化简(sin^2a*cos^4a+sin^4acos^2a)/(1-sin^4a-cos^4a)
化简Sin A + Sin 2A / 1+cos A +
化简:sin(-a)cos(2π+a)sin(-a-π)
化简sin^2a-cos^2a