证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y)

来源:学生作业帮助网 编辑:作业帮 时间:2024/10/01 21:56:14
证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y)
xSJ@Y*cH#M EfH0PHZ- (bkxt51F(Y9;wӵAzynxk>e0C_oksshRf8O(!? [ͮG ӻe7U@,0L!ʽ E*Ubv..f*0 (6\wHkk _L{0TI1( ~<4^p#n8+e%xY1U[x]A

证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y)
证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y)

证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y)
sin(x+y)=sinxcosy+cosxsiny 具体推导:首先建立直角坐标系,在直角坐标系cos(x+y) = cosx cosy - sinx siny sin(x+y) = sinx cosy + cosx

∵sinx=sin[﹙x+y﹚-y]
=sin﹙x+y﹚cosy-cos﹙x﹢y﹚siny
cosx=[﹙x+y﹚-y]
=cos﹙x+y﹚cosy+sin﹙x﹢y﹚siny
∴原式=[sin﹙x+y﹚cosy-cos﹙x﹢y﹚siny+cos﹙x﹢y﹚siny]/[cos﹙x+y﹚cosy+sin﹙x﹢y﹚siny-sin﹙x﹢y﹚siny]
=[sin﹙...

全部展开

∵sinx=sin[﹙x+y﹚-y]
=sin﹙x+y﹚cosy-cos﹙x﹢y﹚siny
cosx=[﹙x+y﹚-y]
=cos﹙x+y﹚cosy+sin﹙x﹢y﹚siny
∴原式=[sin﹙x+y﹚cosy-cos﹙x﹢y﹚siny+cos﹙x﹢y﹚siny]/[cos﹙x+y﹚cosy+sin﹙x﹢y﹚siny-sin﹙x﹢y﹚siny]
=[sin﹙x+y﹚cosy]/[cos﹙x+y﹚cosy]
=sin﹙x+y﹚/cos﹙x+y﹚=tan﹙x+y﹚

收起