解方程:(1)2sin(x/2)=tanx (2)2sin(x/2)=-tanx
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解方程:(1)2sin(x/2)=tanx (2)2sin(x/2)=-tanx
2sin(x/2)=tanx
2sin(x/2)=sinx/cosx
cosx=sinx/2sin(x/2)
cosx=2sin(x/2)cos(x/2)/2sin(x/2)
cosx=cos(x/2)
cosx=2cos平方(x/2)-1=cos(x/2)
设cos(x/2)为x可得方程 2x平方-x-1=0
解得cos(x/2)=1 或-1/2
x/2=0 、 2/3π或4/3π
所以 x=0 、4/3π 8/3π
另一道题与这到题类似就不作解答了
2sin(x/2)=sinx/cosx
cosx=sinx/2sin(x/2)
cosx=2sin(x/2)cos(x/2)/2sin(x/2)
cosx=cos(x/2)
cosx=2cos平方(x/2)-1=cos(x/2)
设cos(x/2)为x可得方程 2x平方-x-1=0
解得cos(x/2)=1 或-1/2
x/2=0 、 2/3π或4/3π
所以 x=0 、4/3π 8/3π
另一道题与这到题类似就不作解答了
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