cos(a+b)=sin(a-b) 求tan a

cos∧a-cos∧b=t则sin(a+b)sin(a-b)= cos(a+b)=sin(a-b) 求tan a sin A+sin b=sinc（cos a+cos b）求三角形是什么形状? Cos(a+b)*cos(a-b)=1/5 求cos ^2-sin^2 解三角函数已知 sin(b)+cos(b)=a 求a的值sin(b)*cos(b)=a cos(a+b)=cos(a)*cos(b)-sin(a)*sin(b) 用三角形证明我 已经证明了sin(a+b)=sin(a)*cos(b)+cos(a)*sin(b) 用 三角形证明 了过程如下： 现在跪求希望大家帮我证明：cos(a+b)=cos(a)*cos(b)-sin(a)*sin(b) 也用 三角形证明 . 求非线性方程组的“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 若sin a+sin b+ sin c=0,cos a+cos b+cos c=0,求cos(a-b) 已知 sin a +sin b =1/4cos a +cos b =1/3求 tan (a+b) 已知sin(a+b)sin(a-b)=-1/3,求cos^2a-cos^2b的值 sin(2A+B)/sinA-cos(A+B)=2,求sin^2(B)+2cos(2A) 已知sin(a+b)sin(b-a)=m,试求cos^2a-cos^2b的值 cos(a+b)cos(a-b)+sin(a+b)sin(a-b)=-3/5,求sin(3π/2+2b) cos(a+B)×cos(a-B)=1/3,求cos^2(a)-sin^2(B)的值 如何证明sin(a+b)=sin(a)cos(b)+cos(α)sin(b) 在三角形中,已知,cos C/cos B=(3a-c)/b 求：sin B sin(a-b)=1,sin a=1/3,求cos b的值RT sin(a-b)=1 ,sin a=1/3 ,求cos b的值