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Math Help - Proofs

  1. #1
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    Proofs

    I need to prove the following:

    1) (1 + cotX)/(cosecX) - (secX)/(tanX + cotA) = cos

    and

    2) (5 - 7cos^2X)(sin^2X) = 5 - 2cot^2X
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by Gilesy View Post
    I need to prove the following:

    1) (1 + cotX)/(cosecX) - (secX)/(tanX + cotA) = cos

    and

    2) (5 - 7cos^2X)(sin^2X) = 5 - 2cot^2X
    Replace all trig functions by the equivalent in terms of sines and cosines and simplify.

    RonL
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  3. #3
    Flow Master
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    Quote Originally Posted by Gilesy View Post
    [snip]
    2) (5 - 7cos^2X)(sin^2X) = 5 - 2cot^2X
    Note that the numerator can be written as 5 - 5 \cos^2 x - 2 \cos^2 x = 5(1 - \cos^2 x) - 2 \cos^2 x = 5 \sin^2 x - 2 \cos^2 x.
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