sin(a-b)*cos a-cos(a-b)*sin a=1/5,则cos 2b的值是

化简COS(a+B)COS(a-B)+sin平方B 化简cos(a+b)cos(a-b)+sin^2b cos(a+b)+cos(a-b)/sin(a+b)+sin(a-b)化简 化简 cos(a-b)cos(a+b)+sin(a-b)sin(a+b). cos(a-b)cos(a+b)+sin(a-b)sin(a+b)化简, 求证cos(a+b)cos(a－b)=cos^2b－sin^2a 求证cos(a+b)cos(a-b)=cos^2a-sin^2b 求证:cos(a+b)cos(a-b)=cos平方b-sin平方a 求证:cos²a-sin²b=cos(a-b)cos(a+b) 非线性方程解析解-x0*cos(b)*cos(c)-y0*(-sin(a)*cos(b)*cos(c)-cos(a)*sin(c))-z0*(-cos(a)*cos(b)*cos(c)+sin(a)*sin(c))=0-x0*cos(b)*sin(c)-y0*(-sin(a)*cos(b)*sin(c)+cos(a)*cos(c))-z0*(-cos(a)*cos(b)*sin(c)-sin(a)*cos(c))=0 -x0*cos(b)-y0*sin(a)*co 化简cos(a-B)cos(a-y)-sin(a-B)sin(y-a) 如何证明sin(a+b)=sin(a)cos(b)+cos(α)sin(b) (cos a+sin a)/(cos a-sin a) 怎么算~ cos^B-cos^C=sin^A,三角形的形状 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) 化简 sin^4a-cos^4b cos(A)*tan(B)*sin(C) sin a sin b +cos a cos b =0,则sin a cos a+sin b cos b的值