sin^4A+cos^2A+sin^2Acos^2A=?

sin^4+sin^2cos^2+cos^2a= 求证1+sin a+cos a+2sin acos a/1+sin a+cos a=sin a+cos a (cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=? cosA+cos^2A=1,sin^2A+sin^4A+sin^8A (1-sin^6a-cos^6a)/(sin^2a-sin^4a) sin/cos^2a+cos/sin^2a最小值 求证:sin 2a/1+sin a+cos a=sin a+cos a-1急 化简：sin^4a+cos^2a-sin^2a-cos^4a 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 (1-sin^4a-cos^4)/(sin^2a-sin^4a) 化简 化简:sin(-a)cos(2π+a)sin(-a-π) 化简Sin A + Sin 2A / 1+cos A + sin^4a-cos^4a=sin^2-cos^2a 一个简单的三角函数题(sin a + cos a)/(sin a - cos a) 则 sin a *cos a=(sin a + cos a)/(sin a - cos a) = 2 则 sin a *cos a= 化简(sin a^2/cos a +cos a)*cot a