求证:tan²θ-sin²θ=tan²θ·sin²θ

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求证:tan²θ-sin²θ=tan²θ·sin²θ
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求证:tan²θ-sin²θ=tan²θ·sin²θ
求证:tan²θ-sin²θ=tan²θ·sin²θ

求证:tan²θ-sin²θ=tan²θ·sin²θ
tan²θ-sin²θ
= sin²θ÷cos²θ-sin²θ
=(sin²θ-sin²θcos²θ)÷cos²θ
= sinθ²(1-cos²θ)÷cos²θ
=(sin²θ÷cos²θ)×(sin²θ÷cos²θ)
= tan²θsin²θ

万能公式

2sin(x-π/4)sin(x π/4)=cos(x-π/4-x-π/4)-cos(x-π/4 x π/4)=-cos2x f(x)=cos(2x-π/3)-cos2x=cos(2x-π/6-π/6)-cos(