````为什么这步可以推出到那步.8sin(a+b/2)cos(b/2)+2cos(a+b/2)sin(b/2)=0=>tan(a+b/2)cot(b/2)=-1/4

Question

````为什么 这步可以推出到那步.
8sin(a+b/2)cos(b/2)+2cos(a+b/2)sin(b/2)=0 =>
tan(a+b/2)cot(b/2)=-1/4

Answer 1

移项8sin(a+b/2)cos(b/2)=-2cos(a+b/2)sin(b/2)
两边同时除以8cos(a+b/2)sin(b/2)
同角的正弦除以余弦等于正切,余弦除以正弦等于余切
所以tan(a+b/2)cot(b/2)=-1/4