Question 213444: Suppose that a circle has an equation of the form x^2 + y^2 =r^2, r>0. What is the center of the circle? What is the radius of the circle?
I am lost since there aren't any numbers to plug into the equation....
Found 2 solutions by rapaljer, drj:
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! The center is at (0,0) and the radius is r. That's it!!
If you need additional help with Circles, you may want to check out my website by doing a "Bing" search for my last name "Rapalje". Look for "Rapalje Homepage" at the top of the search list, and choose the link on my homepage "Math in Living Color." Click on "College Algebra", and look for Section 2.04 "The Circle" at this link. My non-traditional explanation should be easier to understand than your textbook!
R^2
Dr. Robert J. Rapalje, Retired
Seminole Community College
Altamonte Springs Campus
Florida
Answer by drj(1380)  (Show Source):
You can put this solution on YOUR website! Suppose that a circle has an equation of the form x^2 + y^2 =r^2, r>0. What is the center of the circle? What is the radius of the circle?
Step 1. Note this is a distance equation using the Pythagorean Theorem.
Step 2. Note the square of the distance between two points (x,y) and (xc,yc) is:
 where  is the distance or radius.
Step 3. Note that (xc,yc) is the center of a circle. For this example (xc,yc)=(0,0)
I hope the above steps were helpful.
For FREE Step-By-Step videos in Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra and for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.
Good luck in your studies!
Respectfully,
Dr J
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