求证：sin（x-y）/（sinx-siny）=cos[（x-y）/2]/cos[(x+y)/2]（cosy-cosx）/（sinx-siny）=tan[（x+y）/2]

求证sin（2x+y)/sinx-2cos(x+y)=siny/sinx 求证：sin(2x+y)/sinx-2cos(x+y)=siny/sinx y=sinx+sin|x| 求证sinx+siny=2sin(x+y)/2*cos(x-y)/2 求证:sinx+siny=2sin(x+y)/2cos(x-y)/2 求证|sinx-siny|=|2sin[(x-y)/2]cos[(x+y)/2]| 3sinX=sin(2X+Y) 求证：tan(X+Y)=2tanX tan(x+y)=2tany,求证3sinx=sin(x+2y) cos（x+y）sinx-sin（x+y）cosx 求证：sin（x-y）/（sinx-siny）=cos[（x-y）/2]/cos[(x+y)/2]（cosy-cosx）/（sinx-siny）=tan[（x+y）/2] 证明sin(x+y)sin(x-y)=（sinx）^2-(siny）^2. sinx=1/3,sin(x+y)=1,求sin（2y+x）=? 证明sin(x+y)sin(x-y)=sinx-siny 求证：sin(2x+y)/sinx-2cos(x+y)=siny/sinx(2)已知5siny=sin(2x+y),求证:tan(x+y)=3/2 tanx y=sin|x|+|sinx|的图像 求最值：（1）y=-2(sin^2)x+2sinx+1 (2)y=[2sinx-1]/[sinx+3] 已知sinθ+cosθ=2sinx,sinθcosθ=sin²y,求证：4cos²2x=cos²2y 求证 sin^2x/(sinx-cosx)-(sinx+cosx)/tan^2 x-1=sinx+cosx