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1-cosx怎么用半角公式化得2[sin(x/2)]^2
题目详情
1-cosx怎么用半角公式化得 2[sin(x/2)]^2
▼优质解答
答案和解析
1-cosx
=1-(1-2sin^2(x/2))
=2*sin(x/2)^2(半角公式)
cosx
=cos(x/2+x/2)
=cos^2 x/2-sin^2 x/2
=1-2sin^2(x/2)
=1-(1-2sin^2(x/2))
=2*sin(x/2)^2(半角公式)
cosx
=cos(x/2+x/2)
=cos^2 x/2-sin^2 x/2
=1-2sin^2(x/2)
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