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May 16th, 2010, 11:28 AM  #1 
Newbie Joined: May 2010 Posts: 1 Thanks: 0  Finding the center and radius of a circle?
Hi, So I have the following equation: x^212x+84=y^2+16y and I am trying to solve for the center and radius of the circle. I have been able to reduce it to (x6)^2  (y^2 = 16 but the problem is that the standard form of equation is (x  h)^2 + (y  k)^2 = r^2 not (x  h)^2  (y  k)^2 = r^2. Any ideas on how to change  to a +? 
May 16th, 2010, 12:06 PM  #2 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,923 Thanks: 1123 Math Focus: Elementary mathematics and beyond  Re: Finding the center and radius of a circle?
Equation of a conic section: If and the equation is a circle, but . Reference: http://en.wikipedia.org/wiki/Conic_s...an_coordinates 
May 16th, 2010, 03:59 PM  #3 
Global Moderator Joined: Dec 2006 Posts: 20,390 Thanks: 2015 
The equation x²  12x + 84 = y² + 16y reduces to (x  6)²  (y + 8)² = 112. It's not a circle! Should y² have been y²?

May 16th, 2010, 04:00 PM  #4  
Global Moderator Joined: May 2007 Posts: 6,710 Thanks: 675  Re: Finding the center and radius of a circle? Quote:
 
May 16th, 2010, 04:10 PM  #5 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,923 Thanks: 1123 Math Focus: Elementary mathematics and beyond  Re: Finding the center and radius of a circle?
Delete, please.


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center, circle, finding, radius 
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