康熙字典十画的字:一道数学题,很简单,一时忘了怎么做
来源:百度文库 编辑:查人人中国名人网 时间:2024/06/09 07:26:44
根号3tan70+根号3tan80-tan70tan80
tan(70+80)=(tan70+tan80)/(1-tan70tan80)=-1/√3
1-tan70tan80=-√3*(tan70+tan80)
√3tan70+√3*tan80-tan70tan80=-1
=1
tan(70+80)=(tan70+tan80)/(1-tan70tan80)=-1/√3
1-tan70tan80=-√3*(tan70+tan80)
√3tan70+√3*tan80-tan70tan80=-1
=1