证明COS(X+Y)COS(X-Y)=COS^2X-SIN^2Y
证明COS(X+Y)COS(X-Y)=COS^2X-SIN^2Y
sin(x+y)sin(x-y)=k,求cos^2x-cos^2y
sin(x+y)-sinx=2cos(x+1/2y)sin(1/2y)的详细证明步骤.
求证:sin(x-y)/(sinx-siny)=cos[(x-y)/2]/cos[(x+y)/2]
Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y)
请问怎么证明sinX+sin(X+Y)+sin(X+2Y)/cosX+cos(X+Y)+cos(X+2Y)=tan(X+
cos(x+y)=?sin(x+y)=?
y =(cos^2) x - sin (3^x),求y'
化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x)
请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)
证明 [sin(2x+y)/sinx]-2cos(x+y)=siny/sinx
y=cos(-x)求导 1)y=cos(-x)=cos x y'=-sin x 2)y'=-sin(-x)= sin x