My Math Forum  

Go Back   My Math Forum > College Math Forum > Calculus

Calculus Calculus Math Forum


Reply
 
LinkBack Thread Tools Display Modes
March 7th, 2010, 10:23 AM   #1
Newbie
 
Joined: Mar 2010

Posts: 2
Thanks: 0

Finding equation of a circle without knowing its radius

Find the equation of the circle centered at (3,0) that intersects the curve y=x^2 at exactly one point.
aschenbr.rach is offline  
 
March 7th, 2010, 11:52 AM   #2
Global Moderator
 
greg1313's Avatar
 
Joined: Oct 2008
From: London, Ontario, Canada - The Forest City

Posts: 7,923
Thanks: 1123

Math Focus: Elementary mathematics and beyond
Re: Finding equation of a circle without knowing its radius

(x - 3)^2 + y^2 = r^2
x^2 - 6x + 9 + y^2 = r^2
2x - 6 + 2yy' = 0
y' = (6 - 2x)/(2y) and, from the other equation, y' = 2x.
2x = (6 - 2x)/(2y)
2x = (6 - 2x)/(2x^2) [sub in x^2 for y.]
2x - 6 + 4x^3 = 0, x = 1 so r^2 = 5.
greg1313 is offline  
Reply

  My Math Forum > College Math Forum > Calculus

Tags
circle, equation, finding, knowing, radius



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Solve quadratic equation knowing y alexmulo Algebra 8 August 23rd, 2012 06:45 AM
Finding equation of a circle daigo Algebra 1 February 23rd, 2012 03:14 PM
Finding The Standard Equation Of A Circle Given a Point/Line soulrain Algebra 7 January 5th, 2012 07:51 PM
Finding the center and radius of a circle? thyrgle Algebra 4 May 16th, 2010 04:10 PM
Finding a polynomial function by knowing its zeros jokerthief Algebra 3 November 4th, 2007 02:52 PM





Copyright © 2019 My Math Forum. All rights reserved.