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Thread: trigonometry equations

  1. #1

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    trigonometry equations

    Prove the following identities.

    c) (tanx sinx)/tanx - sinx = (tanx + sinx)/(tanx sinx)

  2. #2
    PowerPoster lintz's Avatar
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    Re: trigonometry equations

    It's been a while since I did similtaneous equations but here goes.

    c) (tanx sinx)/tanx - sinx = (tanx + sinx)/(tanx sinx)

    tanx sinx = (tanx + sinx)/(tanx sinx) + sinx * tanx
    tanx = (tanx + sinx)/(tanx sinx) + sinx - (tanx sinx)
    sinx = (tanx + sinx)/(tanx sinx) * tanx - (tanx sinx)

  3. #3
    Addicted Member Glaysher's Avatar
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    Re: trigonometry equations

    Quote Originally Posted by fiery123
    Prove the following identities.

    c) (tanx sinx)/tanx - sinx = (tanx + sinx)/(tanx sinx)
    RHS

    (tanx + sinx)/(tanx sinx) = tan x/[tan x sin x] + sinx/[tan x sin x]

    = 1/sin x + 1/tan x

    = 1/sin x + cos x/sin x

    = [1 + cos x]/sin x

    LHS

    (tanx sinx)/[tanx - sinx] = tan x/[(1/cos x) - 1]

    = sin x/[1 - cos x]

    = sin x[1 + cos x]/[1 - cos2 x]

    = sin x[1 + cos x]/sin2 x

    = [1 + cos x]/sin x

    So LHS = RHS
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  4. #4

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    Re: trigonometry equations

    thanks thanks a lot. sry about forgeting to put brackets around tanx-sinx.

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