Answer
The circle has an equation of $r^2=x^2+y^2$
Work Step by Step
We use the distance formula for a circle with a center of 0,0 to find:
$r = \sqrt{(x-0)^2 + (y-0)^2 } \\ r = \sqrt{x^2+y^2 } \\ r^2 = x^2 +y^2$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.