求证:sin(x-y)/(sinx-siny)=cos[(x-y)/2]/cos[(x+y)/2]
求证:sin(x-y)/(sinx-siny)=cos[(x-y)/2]/cos[(x+y)/2]
求证:sin(2x+y)/sinx-2cos(x+y)=siny/sinx
求证sinx+siny=2sin(x+y)/2*cos(x-y)/2
求证|sinx-siny|=|2sin[(x-y)/2]cos[(x+y)/2]|
证明 [sin(2x+y)/sinx]-2cos(x+y)=siny/sinx
请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)
为什么sin(x+y) - sinx = 2cos(x+y/2)siny/2
证明COS(X+Y)COS(X-Y)=COS^2X-SIN^2Y
证明sin(x+y)sin(x-y)=(sinx)^2-(siny)^2.
cos(x+y)sinx-sin(x+y)cosx
两角和差公式sinx-siny=2sin[(x-y)/2]cos[(x+y)/2]推导.
sin(x+y)-sinx=2cos(x+1/2y)sin(1/2y)的详细证明步骤.