> 数学 >
已知sin(a-pai/4)=1/3,则cos(a+pai/4)=?
人气:446 ℃ 时间:2020-06-13 08:58:06
解答
sin(a-π/4)
=sin[(a+π/4)-π/2]
=-sin[π/2-(a+π/4)]
=-cos(a+π/4)
=1/3
cos(a+π/4)=-1/3
推荐
猜你喜欢
© 2026 79432.Com All Rights Reserved.
电脑版|手机版