已知x-y=派/3,且sin x-siny=1/2,求cos(x+y).
已知x-y=派/3,且sin x-siny=1/2,求cos(x+y).
已知sin(2x-y)5/13,siny=-3/5,x属于(派/2,派),y属于(-派/2,0),求sinx的值
已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).
已知x,y,z属于(0,派/2),sin^2x+sin^2y+sin^2z=1,求(sinx+siny+sinz)/(c
已知cos(x+y)cosy+sin(x+y)siny=4/5,求tanx的值
已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y)
已知:3sinY=sin(2X+Y),求证tan(X+Y)=2tanX
已知5siny=sin(2x+y),求证:tan(x+y)=3/2tanx
求证:sin(x-y)/(sinx-siny)=cos[(x-y)/2]/cos[(x+y)/2]
请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)
求证sinx+siny=2sin(x+y)/2*cos(x-y)/2
求证|sinx-siny|=|2sin[(x-y)/2]cos[(x+y)/2]|