化简：cos^4a-sin^4a=

化简(1-sin^6 a-cos^6 a)/(cos^2 a-cos^4 a)== sin^4+sin^2cos^2+cos^2a= cos^4A-sin^4a 化简 Sin^4a-cos^4a= 化简：cos^4a-sin^4a= 化简cos^4(a/2)-sin^4(a/2)= 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 化简：sin^4a+cos^2a-sin^2a-cos^4a （1-sin^6a-cos^6a)/(1-sin^4a-cos^4a)=? sin^4a-cos^4a=sin^2a-cos^2a 证明sin^4a-cos^4a=sin^2a-cos^2a sin∨4a-cos∨4a=sin²a-cos²a 求证 tan a =3求4sin a-2cos a/5cos+3sin a 化简 sin^4a-cos^4b 化简 1-sin^4a-cos^4a/cos^2a-cos^4a 化简cos^4 a-sin^4 a+2sin^2 a= 化简sin(A+π/4)sin(A-π/4)/sin^4A-cos^4A