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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^2-12x+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 (x-6)^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: 7,946 Thanks: 1137 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: 20,751 Thanks: 2135 The equation x� - 12x + 84 = y� + 16y reduces to (x - 6)� - (y + 8)� = -112. It's not a circle! Should y� have been -y�? May 16th, 2010, 04:00 PM   #4
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Re: Finding the center and radius of a circle?

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 Originally Posted by thyrgle Hi, So I have the following equation: x^2-12x+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 (x-6)^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 +?
You can't - you've got a hyperbola. May 16th, 2010, 04:10 PM #5 Global Moderator   Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,946 Thanks: 1137 Math Focus: Elementary mathematics and beyond Re: Finding the center and radius of a circle? Delete, please. Tags center, circle, finding, radius Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post daveyf Probability and Statistics 8 April 25th, 2011 07:32 AM smog890 Algebra 3 October 4th, 2010 06:42 PM aschenbr.rach Calculus 1 March 7th, 2010 11:52 AM rune2402 Algebra 4 February 27th, 2008 05:21 PM Igo Calculus 1 December 31st, 1969 04:00 PM

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