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Math Help - Finding the radius of a circle

  1. #1
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    Finding the radius of a circle

    Hey guys I have a question. I'm helping my dad build a desk and he needs to find the radius of a circle created by an arc on the bottom on the desk. The only measurements we have are in this poorly drawn picture below. I tried multiple methods and came up with the answer around 56. I could use some reassurance though, thanks for the help.
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  2. #2
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    Re: Finding the radius of a circle

    Quote Originally Posted by levunit View Post
    Hey guys I have a question. I'm helping my dad build a desk and he needs to find the radius of a circle created by an arc on the bottom on the desk. The only measurements we have are in this poorly drawn picture below. I tried multiple methods and came up with the answer around 56. I could use some reassurance though, thanks for the help.
    1. I've "completed" your sketch such that you can see that actually you are dealing with a right triangle.

    2. In a right triangle the square of the height equals the product of the two hypotenuse segments. With your values:

    (2r-6) \cdot 6 = 40^2

    3. Solve for r. I've got r = 136.33
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  3. #3
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    Re: Finding the radius of a circle

    Thanks for the help, but may I ask why (2r - 6)*6=1600? I'm a little rusty when it comes to this stuff.

    EDIT: Nevermind, I skipped a line. I understand now. Thanks!
    Last edited by levunit; April 5th 2012 at 02:00 PM.
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