π〈α〈2π且f(α）={√2-2 cosα}/{

1个回答

令cosα/2=t,sinα/2=s
（1-sinα-cosα）（cosα/2+sinα/2）= [(s-t)^2-(t^2-s^2)](t+s)
=(s-t)(s^2-t^2)+(s+t)(s^2-t^2) = 2s(s^2-t^2)=-2sinα/2*cosα
就这样,分子基本上不能有实质化简.

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