> 数学 >
cos(a+π/)=-1/3 a∈(0,π/2) 求coSa
人气:311 ℃ 时间:2020-06-16 12:43:43
解答
cos(a+π/2)=-1/3
cosacosπ/2-sinasinπ/2=-1/3
-sina=-1/3
sina=1/3
∵a∈(0,π/2)
∴cos²a =1-sin²a
=2根号2/3
推荐
猜你喜欢
© 2026 79432.Com All Rights Reserved.
电脑版|手机版