How did you get the radius?
Since this is an equation for an ellipse, not a circle, you will not be able to find a radius. Instead, you are looking for the vertices along the major and minor axes. To do that, divide the equation through by 4 so that the right-hand side is 1 to get: \frac{(x+2)^2}{4}+\frac{(y-1)^2}{\frac{4}{3}}=1 This is the standard form for an ellipse: \frac{(x-h)^2}{a^2}+\frac{(y-k)^2}{b^2}=1 where the center of the ellipse is at the point (h,k), a is the distance from the center to the vertices along the major axis, and b is the distance from the center to the vertices along the minor axis. For this particular ellipse, the center is at (-2,1), a=2, and b=\frac{2\sqrt{3}}{3}. The ellipse looks like this: