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Math Help - Give an expression

  1. #1
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    Give an expression

    The minute hand on a clock is 8 cm long and the hour hand is 5 cm long. Give an expression for d, the distance between the tips of the hands, in terms of a, the angle between the hands.


    D=



    I've been trying to figure this out for the past hour... needless to say, I just have problems with these questions.
    Last edited by gearshifter; November 1st 2008 at 04:19 PM.
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  2. #2
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    Quote Originally Posted by gearshifter View Post
    The minute hand on a clock is 8 cm long and the hour hand is 5 cm long. Give an expression for d, the distance between the tips of the hands, in terms of a, the angle between the hands.


    D=



    I've been trying to figure this out for the past hour... needless to say, I just have problems with these questions.
    It would seem that this is a classic application of the law of cosines.

    You have an angle a included between two sides 8 and 5. The side opposite angle a, which is D is the distance between the the two hands.

    D^2=8^2+5^2-2(8)(5)\cos a

    D=\sqrt{8^2+5^2-2(8)(5)\cos a}

    Can you simplify?
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