Question 220101: I've tried this a couple different ways, but the answer wasn't right.
I know that the standard equation for a circle with the center at the origin is
X^2 + Y^2= r^2
but I can't figure out how to find the radius.
Center at origin and containing the point (-2,3)
I've tried using the midpoint formula, distance formula and also inputing the given point into the standard equation for which I got 15. But I'm supposed to end up with 13 for the radius. What am I doing wrong?
Found 3 solutions by susanaramya, nerdybill, MathTherapy:
Answer by susanaramya(12)   (Show Source):
Answer by nerdybill(7384)  (Show Source):
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website! Looking at the equation,  , we can see many things. For one, this circle-equation has its center at the coordinate point (0, 0) on the coordinate plane, as no (h, k) is visible, thereby making (h, k), (0. 0). Plus, “r” is considered to be the radius. Having this information, plus a point (-2, 3) on the circle, we just substitute to find “r.”
-------> 
Therefore, r, or radius = 
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