sin a-cos a=5/4,则sin2a的值为?

tan a =3求4sin a-2cos a/5cos+3sin a sin^4+sin^2cos^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= sin(a-b)*cos a-cos(a-b)*sin a=1/5,则cos 2b的值是 Sin^4a-cos^4a= 已知(4sin a－2cos a)／(5cos a +3sin a)=6/11,求cos＾4 a－sin＾4 a 已知sin a-2cos a=0 求4sin^2 a-3sin a x cos a-5cos^2 a的值 8sin(45+a)sin(45-a)=1,sin^4a-cos^4a= cosA+cos^2A=1,sin^2A+sin^4A+sin^8A (cos a)^4+(sin a)^2*(sin a)^2+(sin a)^2=? 已知tan(a)=3,则sin^a-3sin(a)cos(a)+4cos^a=? 已知tan a=-1/3,求4sin a-2cos a/5cos a+3sin a= 已知tan a=2,求:(4*sin a-2*cos a)/(5*sin a+3*cos a)的值 sin a-cos a=1/5,则sin 2a= 请问数学题,设sin a+cos a=3/5,则sin 2a=? 若sin a -cos a=-5/4. 则sin 2a 值为 求证1+sin a+cos a+2sin acos a/1+sin a+cos a=sin a+cos a 若sin^4 a+cos^4 a=1,则sin a=cos a的值为