若f(cosθ﹚=sin²θ-3cosθ,则f﹙2cosπ/3﹚=___?
2个回答
f(cosθ﹚=sin²θ-3cosθ
f(cosθ)=1-cos²θ-3cosθ
则:
f(x)=1-x²-3x
f(2cosπ/3)=f(1)
=1-1-3
=-3
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