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Thread: Trig Proof

  1. #1
    Member jacs's Avatar
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    Trig Proof

    I have a trig proof i have come at from every way i can think of and just can't make it work

    If a/sin A = b/cos A, show that sin A cos A = (ab)/(a^2 + b^2)

    thanks
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  2. #2
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    Quote Originally Posted by jacs View Post
    I have a trig proof i have come at from every way i can think of and just can't make it work

    If a/sin A = b/cos A, show that sin A cos A = (ab)/(a^2 + b^2)

    thanks
    \displaystyle\frac{a}{SinA}=\frac{b}{CosA}\Rightar  row\ \frac{a}{b}=\frac{SinA}{CosA},\ \frac{b}{a}=\frac{CosA}{SinA}

    Then

    \displaystyle\frac{a}{b}+\frac{b}{a}=\frac{a^2+b^2  }{ab}

    Work that out and invert the result.
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  3. #3
    Member jacs's Avatar
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    Thanks, figured it out now. Never would have thought to do it that way on my own!
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