Grigori S. answered 05/14/13
Certified Physics and Math Teacher G.S.
This is a circle with radius R = 3 centered in the origin of a coordinate system. Equation of these circles with the radius R is
x2 + y2 = R 2
R2 = 9. Thus, R = 3. Equations for ellipse, parabola, and hyperbola are different from this one, but they all belong to the family of conic sections.