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Math Help - Cosine...

  1. #1
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    Question Cosine...

    If cos^{-1}(x)+cos^{-1}(y)=\frac{\pi}{2},
    show that x^2+y^2=1

    Haha, help please?
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  2. #2
    Senior Member apcalculus's Avatar
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    Quote Originally Posted by fizz View Post
    If cos^{-1}(x)+cos^{-1}(y)=\frac{\pi}{2},
    show that x^2+y^2=1

    Haha, help please?
    Let
    cos^{-1}(x) = m
    cos^{-1}(y) = n

    So we have:
    m + n = \frac{\pi}{2}

    Also, from above, we have:

    x= \cos m
    y= \cos n

    Can you finish the rest?

    Good luck!
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