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Thread: proving identities

  1. November 28th 2009, 11:37 AM #1
    Cooks
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    proving identities

    please i need help with this problem.

    cosB/1-tanB + sinB/1-cotB = sinB + cosB

    how can i prove this identity?
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  2. November 28th 2009, 01:13 PM #2
    skeeter
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    Quote Originally Posted by Cooks View Post
    please i need help with this problem.

    cosB/1-tanB + sinB/1-cotB = sinB + cosB

    how can i prove this identity?
    working on the left side ...

    \frac{\cos{\beta}}{\cos{\beta}} \cdot \frac{\cos{\beta}}{1-\tan{\beta}} + \frac{\sin{\beta}}{\sin{\beta}} \cdot \frac{\sin{\beta}}{1-\cot{\beta}}

    \frac{\cos^2{\beta}}{\cos{\beta} - \sin{\beta}} + \frac{\sin^2{\beta}}{\sin{\beta}-\cos{\beta}}

    \frac{\cos^2{\beta}}{\cos{\beta} - \sin{\beta}} - \frac{\sin^2{\beta}}{\cos{\beta} - \sin{\beta}}

    \frac{\cos^2{\beta}-\sin^2{\beta}}{\cos{\beta} - \sin{\beta}}

    factor the numerator and finish it up ...
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  3. December 1st 2009, 02:12 AM #3
    mrmohamed
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    Quote Originally Posted by Cooks View Post
    please i need help with this problem.

    cosB/1-tanB + sinB/1-cotB = sinB + cosB

    how can i prove this identity?
    hi all


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