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Thread: Equation of a circle

  1. #1

    Equation of a circle

    How to find and solve the equation of a circle with radius 5 radical 2 and center (-3,2)???

  2. #2
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    Quote Originally Posted by Carmen8722 View Post
    How to find and solve the equation of a circle with radius 5 radical 2 and center (-3,2)???
    Standard equation of a circle is:

    [TEX](X-H)^2 + (Y-K)^2 \:=\: R^2[/TEX]

    So you would fill in;

    [TEX](X + 3)^2 + (Y - 2)^2 \:=\: 25[/TEX]
    Last edited by Walter; 02-27-2012 at 09:17 PM.

  3. #3
    this answer is ???


    Quote Originally Posted by Walter View Post
    Standard equation of a circle is:

    [TEX](X-H)^2 + (Y-K)^2 \:=\: R^2[/TEX]

    So you would fill in;

    [TEX](-3 - H)^2 + (2 - K)^2 \:=\: 25[/TEX]

  4. #4
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    Quote Originally Posted by Carmen8722 View Post
    How to find and solve the equation of a circle with radius 5 radical 2 and center (-3,2)???
    The general form for the equation of a circle with center (h, k) and radius r is

    (x - h)2 + (y - k)2 = r2

    You are GIVEN the center: (-3, 2) so if (h, k) = (-3, 2) then h = -3 and k = 2.

    You are GIVEN that the radius is 5 sqrt(2)...that's r.

    The equation of the circle in standard form, then, is

    (x - (-3))2 + (y - 2)2 = [5 sqrt(2)]2


    Can you do some simplification?

    '

  5. #5
    This answer: ... right??


    Quote Originally Posted by Mrspi View Post
    The general form for the equation of a circle with center (h, k) and radius r is

    (x - h)2 + (y - k)2 = r2

    You are GIVEN the center: (-3, 2) so if (h, k) = (-3, 2) then h = -3 and k = 2.

    You are GIVEN that the radius is 5 sqrt(2)...that's r.

    The equation of the circle in standard form, then, is

    (x - (-3))2 + (y - 2)2 = [5 sqrt(2)]2


    Can you do some simplification?

    '

  6. #6
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    He's right, I got the equation mixed up, the answer would be;
    [TEX](X + 3)^2 + (Y - 2)^2 \:=\: 25[/TEX]

  7. #7
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    Quote Originally Posted by Walter View Post
    He's right, I got the equation mixed up, the answer would be;
    [TEX](X + 3)^2 + (Y - 2)^2 \:=\: 25[/TEX]
    Walter, I think you (and the original poster!) need to double-check your arithmetic.

    [5 sqrt(2)]2 is NOT 25.....

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