SOLUTION: How could I find the general form of the equation of this circle: Center at the origin and containing the point (-2,3)

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Question 397322: How could I find the general form of the equation of this circle: Center at the origin and containing the point (-2,3)
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Start with:
%28x-h%29%5E2%2B%28y-k%29%5E2+=+r%5E2 This is the general equation of a circle with center at (h, k) and a radius of r.
In your problem, the center is at the origin (0, 0) so you can write:
x%5E2%2By%5E2+=+r%5E2 To find r%5E2, just substitute the x- and y-coordinates of the given point (-2, 3) into this equation and solve for r%5E2
%28-2%29%5E2%2B%283%29%5E2+=+r%5E2
4%2B9+=+r%5E2 so...
r%5E2+=+13
The final equation is:
x%5E2%2By%5E2+=+13