sin(a)*cos(a)=4,那么sin(a) cos(b)=?

sin(a)*cos(a)=4,那么sin(a) cos(b)=? sin a+cos a=1/2.那么sin a*cos a= 已知tan a=cos a,那么sin a= cos^2a-cos^2b=m,那么sin(a+b)sin(a-b)=? sin^4+sin^2cos^2+cos^2a= Sin^4a-cos^4a= 如果tan a=2,那么sin a*sin a+sin a*cos a+cos a*cos a的值是（ ）A:7/3B:7/5C:5/4D:5/3 （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(1-sin^6 a-cos^6 a)/(cos^2 a-cos^4 a)== 如果2sin a=cos a,那么cos^2等于多少? 8sin(45+a)sin(45-a)=1,sin^4a-cos^4a= 由cos(a+b)=cos a cos b-sin a sin b cos(a-b)=cos a cos b+sin a sin b解题设a为锐角,证：1、2分之根3乘cos a + 2分之1乘sin a=cos(6分之π-a)2、cos a-sin a=根号2cos(4分之π+a) cosA+cos^2A=1,sin^2A+sin^4A+sin^8A (cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=?