化简：sin^4a+cos^2a-sin^2a-cos^4a

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Sin A + Sin 2A / 1+cos A + 化简:sin(-a)cos(2π+a)sin(-a-π) 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 化简sin^2a-cos^2a (cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=? (1-sin^6a-cos^6a)/(sin^2a-sin^4a) 化简cos^4(a/2)-sin^4(a/2)= Sin^4a+Sina*Cosa+Cos^2a化简 化简sin a+cos a