cos(a+b)+cos(a-b)/sin(a+b)+sin(a-b)化简
问题描述：
cos(a+b)+cos(a-b)/sin(a+b)+sin(a-b)化简
答
原式
=2cosa*cosb/(2sina*cosb)
=cota
答
=(cosacosb-sinasinb+cosacosb+sinasinb)/(sinacosb+cosasinb+sinacosb-cosasinb)
=2cosacosb/2sinacosb
=cota