存在一对x,y属于R,sin(x-y)=sinx-siny是真命题么?

若sinx=siny,则x=y 是真命题吗?互为什么条件 证明sin(x+y)sin(x-y)=sinx-siny 求函数z=sinx+siny+sin(x+y)(0 求sin(x+y)=sinx+siny的导数 若命题"存在x属于R,sin^2X+2sinX+m=0"为真命题,求实数m的取值范围 证明sinx+siny+sinz-sin(x+y+z)=4sin((x+y)/2)sin((x+y)/2)sin((x+ 求下列导数：sin(x+y)=sinx+siny e^x+x=e^y+y 证明 [sin(2x+y)/sinx]-2cos(x+y)=siny/sinx 求证：sin(2x+y)/sinx-2cos(x+y)=siny/sinx 证明sin(x+y)sin(x-y)=（sinx）^2-(siny）^2. 已知x,y,z属于(0,派/2),sin^2x+sin^2y+sin^2z=1,求(sinx+siny+sinz)/(c 请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)