证明tanα+secα=tan(α/2+π/4)
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证明tanα+secα=tan(α/2+π/4)
证明tanα+secα=tan(α/2+π/4)
证明tanα+secα=tan(α/2+π/4)
tanα=2tan(α/2)/[1-tan(α/2)*tan(α/2)]
secα=[1+tan(α/2)*tan(α/2)]/[1-tan(α/2)*tan(α/2)]
tanα+secα=2tan(α/2)/[1-tan(α/2)*tan(α/2)]+[1+tan(α/2)*tan(α/2)]/[1-tan(α/2)*tan(α/2)]
=[1+2tan(α/2)+tan(α/2)*tan(α/2)]/[1-tan(α/2)*tan(α/2)]
=[(1+tan(α/2))^2]/[(1+tan(α/2))(1-tan(α/2))]=(1+tan(α/2))/(1-tan(α/2))=tan(α/2+π/4)
tanα+secα=sinα/cosα+1/cosα=(1+sinα)/cosα
=(sinα/2+cosα/2)²/(cos²α/2-sin²α/2)
=(sinα/2+cosα/2)²/[(cosα/2-sinα/2)(cosα/2+sinα/2)]
=(sinα/2+cosα/2)/(cosα/2-sinα/2)
=(1...
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tanα+secα=sinα/cosα+1/cosα=(1+sinα)/cosα
=(sinα/2+cosα/2)²/(cos²α/2-sin²α/2)
=(sinα/2+cosα/2)²/[(cosα/2-sinα/2)(cosα/2+sinα/2)]
=(sinα/2+cosα/2)/(cosα/2-sinα/2)
=(1+tanα/2)/(1-tanα/2)
=(tanπ/4+tanα/2)/(1-tanπ/4tanα/2)
=tan(α/2+π/4)
∴tanα+secα=tan(α/2+π/4)
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