cosa=根号(1-sina^2)=4根号3/7
sin(a+b)=11/14
cosb=cos(a+b-a)=cos(a+b)cosa+sin(a+b)sina
=71/98
sinb=根号(1-cosb^2)= 39根号3/98
已知α、β都是锐角,sinα=1/7,cos(α+β)=(5根号下3)/14.
已知α、β都是锐角,sinα=1/7,cos(α+β)=(5根号下3)/14.
求(1)试用α与α+β表示β(2)求sinβ、cosβ的值
求(1)试用α与α+β表示β(2)求sinβ、cosβ的值
数学人气:566 ℃时间:2019-10-23 07:45:30
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