作业帮 > 数学 > 作业

cos(x+y)-cosx如何等于-2sin[(2x+y)/2]sin(y/2),

来源：学生作业帮 编辑：百度作业网作业帮 分类：数学作业 时间：2024/06/07 01:18:46
cos(x+y)-cosx如何等于-2sin[(2x+y)/2]sin(y/2),
cos(x+y)-cosx如何等于-2sin[(2x+y)/2]sin(y/2),
x+y=(2x+y)/2+(y/2) x=(2x+y)/2-(y/2)
cos(x+y)-cosx=cos[(2x+y)/2+(y/2)]-cos[(2x+y)/2-(y/2)]
=cos[(2x+y)/2]*cos(y/2)-sin[(2x+y)/2]*sin(y/2)-cos[(2x+y)/2]*cos(y/2)-sin[(2x+y)/2]*sin(y/2)
=-2sin[(2x+y)/2]sin(y/2)
函数y=cos^3x+sin^2x-cosx的最大值等于? 化简sin(2x-y)*sin y+cos(2x-y)*sin y sinx*sin(x+y)+cosx*cos(x+y)等于? 化简sin(x+y)sinx+cos(x+y)cosx等于? 请问怎么证明sinX+sin(X+Y)+sin(X+2Y)/cosX+cos(X+Y)+cos(X+2Y)=tan(X+ sin(x+y)sin(x-y)=k,求cos^2x-cos^2y y =(cos^2) x - sin (3^x),求y' 证明COS（X+Y）COS（X-Y）=COS^2X-SIN^2Y y=sin^2x+2sinx*cosx+3cos^2x 函数y=sin²x-cos²x+2cosx-2的最大值是? y=sin²X+2sinX*cosX+3COS²X的最大值是? Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y)