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Math Help - verifying trig identities

  1. #1
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    verifying trig identities

    Could someone please explain to me how to get through to the next step of verifying the identity?

    <br />
cos^3 x  sin^2 x = (sin^2 x - sin^4 x) cos x <br />

    <br />
cos x(sin^2 x - sin^4 x) =<br />

    <br />
cos x sin^2 x - sin^4 x cos x = <br />


    What Next?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by robasc View Post
    I am tyring to prove that:

    <br />
cos^3 x  sin^2 x<br />


    Equals:
    <br />
(sin^2 x - sin^4 x) cos x<br />
    Prove \cos^3 x \sin^2 x \equiv (\sin^2 x - \sin^4 x) \cos x

    Consider the LHS

    \cos^3 x \sin^2 x = \cos x \cos^2 x \sin^2 x

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

    = \cdots
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  3. #3
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    Prove

    Consider the LHS





    __________________

    So the next move would be:

    <br />
cos x(1 - sin^2 x) sin^2 x = <br />

    <br />
cos x(sin^2 x - sin^4 x)<br />

    and that's it!
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