若sin+2a=1/3,则cos+4a=
1个回答
关注
![]()
展开全部
(1+sin4a-cos4a)/(1+sin4a-cos2a)=(sin²2a+cos²2a+2sin2acos2a+(cos²2a-sin²2a)/(sin²2a+cos²2a+2sin2acos2a--cos2a)=2cos2a(cos2a+sin2a)/[(sin2a+cos2a)²-cos2a] =2/[(sin2a+cos2a)/(cos2a)-1/(sin2a+cos2...
咨询记录 · 回答于2022-03-02
若sin+2a=1/3,则cos+4a=
您好，您的问题我已经看到了，正在整理答案，请稍等一会儿哦~
若sin+2a=1/3,则cos+4a=
cos^(a-π/4)=[1+cos2(a-π/4)]/2 =[1+cos(2a-π/2)]/2 =(1+sin2a)/2 =(1+1/3)/2 =2/3
若sin+2a=1/3,则cos+4a=
sin cos tan
若sin+2a=1/3,则cos+4a=
(1+sin4a-cos4a)/(1+sin4a-cos2a)=(sin²2a+cos²2a+2sin2acos2a+(cos²2a-sin²2a)/(sin²2a+cos²2a+2sin2acos2a--cos2a)=2cos2a(cos2a+sin2a)/[(sin2a+cos2a)²-cos2a] =2/[(sin2a+cos2a)/(cos2a)-1/(sin2a+cos2...
已赞过
评论
收起
你对这个回答的评价是？