已知5siny=sin(2x+y),求证:tan(x+y)=3/2tanx
人气:166 ℃ 时间:2020-03-28 19:13:25
解答
sin[(x+y)+x]=5sin[(x+y)-x]
sin(x+y)·cosx+cos(x+y)·sinx=5·sin(x+y)·cosx-5·cos(x+y)·sinx
4·sin(x+y)·cosx=6·cos(x+y)·sinx
两边同除以cos(x+y)·cosx得:2·tan(x+y)=3·tanx
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