数学 sin(x/2) = 2/3 [0≤x≤pi/2] cosx? tanx? sin(x/4) =?
来源:百度知道 编辑:UC知道 时间:2024/05/21 17:37:50
数学 sin(x/2) = 2/3 [0≤x≤pi/2]
怎样求:(要程序!1)
cosx? tanx? sin(x/4) =?
怎样求:(要程序!1)
cosx? tanx? sin(x/4) =?
cosx=1-2sin^(x/2)=1/9
又:sinx=根号下(1-cos^x)=根号下80/9
所以:tanx=sinx/cosx=根号下80
又:cos(x/2)=根号下{1-sin^(x/2)}=根号下5/3
所以:sin(x/4) =根号下{[1-cos(x/2)]/2}=……
再解一下就可以了〉
应该有个二倍角公式吧
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