若sinx+sinz=2siny,求证:tan((x+y)/2)+tan((y+z)/2)=2tan((x+z)/2)

已知sinx+siny+sinz=cosx+cosy+cosz=0,求tan(x+y+z)+tanxtanytanz的值 证明sinx+siny+sinz-sin(x+y+z)=4sin((x+y)/2)sin((x+y)/2)sin((x+ 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 已知x,y,z属于(0,派/2),sin^2x+sin^2y+sin^2z=1,求(sinx+siny+sinz)/(c tan(x+y)=2tanx(x,x+y≠kπ+π/2,k∈Z),证3siny=sin(2x+y) 3sinX=sin(2X+Y) 求证：tan(X+Y)=2tanX 均值不等式的疑问x+y+z = pi ,求 sinx+siny+sinz 的最大值这题用和差化积做是(3/2)*根号2, sinx+siny=1/3 ,cosx+cosy=1/2,求tan(x+y)的值． 求证:tan(3x/2)-tan(x/2)=(2sinx)/(cosx+cos2x) 求证:tan(3x/2)-tan(x/2)=2sinx/(cosx+cos2x) 已知sinx-siny=-2/3,cosx-cosy=2/3,且x.y为锐角,则tan（x-y）的值为?