《商君书》的驭民五术:帮帮我!!化简sin4a/(1+cos4a)*cos2a/(1+cos2a)*cosa/(1+cosa)*cos(a/2)/(1+cos(a/2))的过程

来源:百度文库 编辑:高校问答 时间:2024/05/08 08:02:26

sin4a/(1+cos4a)*cos2a/(1+cos2a)*cosa/(1+cosa)*cos(a/2)/(1+cos(a/2))=
2sin2a*cos2a/(2cos2acos2a)*cos2a/(1+cos2a)*cosa/(1+cosa)*cos(a/2)/(1+cos(a/2))=sin2a/(1+cos2a)*cosa/(1+cosa)*cos(a/2)/(1+cos(a/2))=
以同法化简
=sin(a/2)/(1+cos(a/2))=tan(a/4)