两角和差公式sinx-siny=2sin[(x-y)/2]cos[(x+y)/2]推导.
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两角和差公式sinx-siny=2sin[(x-y)/2]cos[(x+y)/2]推导.
两角和差公式
sinx-siny
=2sin[(x-y)/2]cos[(x+y)/2]
推导.
两角和差公式sinx-siny=2sin[(x-y)/2]cos[(x+y)/2]推导.
sinx-siny
=sin[(x-y)/2 + (x+y)/2] -sin[(x+y)/2 -(x-y)/2] (变形后再利用两角和与差的正弦公式)
=sin[(x-y)/2]cos[(x+y)/2] +cos[(x-y)/2]sin[(x+y)/2] -{sin[(x+y)/2]cos[(x-y)/2] -cos[(x+y)/2]sin[(x-y)/2]}
=2sin[(x-y)/2]cos[(x+y)/2]
两角和差公式sinx-siny=2sin[(x-y)/2]cos[(x+y)/2]推导.
sinx*siny=?正余弦的和差化积和积化和差公式谁帮忙总结下啊
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