若f(cosθ﹚=sin²θ-3cosθ,则f﹙2cosπ/3﹚=___?
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![若f(cosθ﹚=sin²θ-3cosθ,则f﹙2cosπ/3﹚=___?](/uploads/image/z/4035881-65-1.jpg?t=%E8%8B%A5f%28cos%CE%B8%EF%B9%9A%3Dsin%26%23178%3B%CE%B8%EF%BC%8D3cos%CE%B8%2C%E5%88%99f%EF%B9%992cos%CF%80%EF%BC%8F3%EF%B9%9A%EF%BC%9D_%EF%BC%BF_%3F)
若f(cosθ﹚=sin²θ-3cosθ,则f﹙2cosπ/3﹚=___?
若f(cosθ﹚=sin²θ-3cosθ,则f﹙2cosπ/3﹚=___?
若f(cosθ﹚=sin²θ-3cosθ,则f﹙2cosπ/3﹚=___?
f(cosθ﹚=sin²θ-3cosθ
f(cosθ)=1-cos²θ-3cosθ
则:
f(x)=1-x²-3x
f(2cosπ/3)=f(1)
=1-1-3
=-3
f(cosθ﹚=sin²θ-3cosθ
f(cosθ)=1-cos²θ-3cosθ
x=cosθ
f(x)=1-x²-3x
f(2cosπ/3)=f(1)
=1-1-3
=-3