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Math Help - center and radius of a circle?

  1. #1
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    center and radius of a circle?

    how do you find the center and radius of a circle?

    Problem:
    Find the center of the circle given in general form (x^2)+(y^2)-10x-2y+50=49
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by lsnyder View Post
    how do you find the center and radius of a circle?

    Problem:
    Find the center of the circle given in general form (x^2)+(y^2)-10x-2y+50=49
    Hint: x^2+y^2-10x-2y+50=49\implies x^2+y^2-10x-2y+25+1+24=49

    Group the proper terms together, such that you generate perfect squares.

    Can you take it from here?
    Last edited by Chris L T521; January 29th 2009 at 09:40 PM. Reason: caught a typo on my part!! >_<
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    Quote Originally Posted by Chris L T521 View Post
    Hint: x^2+y^2-10x-2y+50=49\implies x^2+y^2-10x-2y+25+4+21=49

    Group the proper terms together, such that you generate perfect squares.

    Can you take it from here?






    i don't fully understand, sorry...........
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  4. #4
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by lsnyder View Post
    i don't fully understand, sorry...........
    I'll show the next step.

    You should group the terms as follows : \left(x^2-10x+25\right)+\left(y^2-2y+1\right)=49-24

    The terms in parenthesis on the LHS of the equation factor as perfect squares. On the right side, you'll have the radius value squared.

    Can you continue from here?



    EDIT: Please refer to my first post. I fixed an error I found in it.
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  5. #5
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    Quote Originally Posted by Chris L T521 View Post
    I'll show the next step.

    You should group the terms as follows : \left(x^2-10x+25\right)+\left(y^2-2y+1\right)=49-24

    The terms in parenthesis on the LHS of the equation factor as perfect squares. On the right side, you'll have the radius value squared.

    Can you continue from here?



    EDIT: Please refer to my first post. I fixed an error I found in it.


    i understand now, thank you very much!
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