化简cos^4 a-sin^4 a+2sin^2 a=

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)== sin^4+sin^2cos^2+cos^2a= (1-sin^4a-cos^4)/(sin^2a-sin^4a) 化简 cos^4A-sin^4a 化简 化简cos^2 a(2cos^2 a+3)-sin^2 a(2cos^2 a+3)-4sin^2 a cos^2 a +3 4sin(a/4)cos(a/4)cos(a/2)cosacos2a化简,a是某角. 化简cos^4(a/2)-sin^4(a/2)= 化简cos^4(a/2)-sin^4(a/2) Sin^4a+Sina*Cosa+Cos^2a化简 化简1-sin^4a-cos^4a/1-sin^6a-cos^6a 1-sin^6a-cos^6a分之1-sin^4a-cos^4a 化简 sin^4a-cos^4a=sin^2a-cos^2a 证明sin^4a-cos^4a=sin^2a-cos^2a 用 cos a表示 sin^4 a-sin^2 a+cos^2 a tan a =3求4sin a-2cos a/5cos+3sin a 化简 sin^4a-cos^4b