
Algebra PreAlgebra and Basic Algebra Math Forum 
 LinkBack  Thread Tools  Display Modes 
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: 7,946 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 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: 6,770 Thanks: 700  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: 7,946 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  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
binomial theory,center+radius of circle,functions(solved)  daveyf  Probability and Statistics  8  April 25th, 2011 07:32 AM 
Finding angle between center of circle and a point on circl  smog890  Algebra  3  October 4th, 2010 06:42 PM 
Finding equation of a circle without knowing its radius  aschenbr.rach  Calculus  1  March 7th, 2010 11:52 AM 
radius and center of circle:graphing  rune2402  Algebra  4  February 27th, 2008 05:21 PM 
Find center and radius  Igo  Calculus  1  December 31st, 1969 04:00 PM 