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Thread: Proving something is equal to tan x

  1. May 6th 2008, 04:05 AM #1
    nerdzor
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    Proving something is equal to tan x

    (sin 2x + sin x) / (cos 2x + cos x+1) = tan x
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  2. May 6th 2008, 04:09 AM #2
    mr fantastic
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    Quote Originally Posted by nerdzor View Post
    (sin 2x + sin x) / (cos 2x + cos x+1) = tan x
    Substitute the double angle formula into the left hand side:

    \sin(2x) = 2 \sin x \cos x

    \cos (2x) = 2 \cos^2 x - 1

    Simplify. Factorise. Cancel the common factor. Viola!
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