If you want to draw a sphere you can do it, it has a nice equation:
r ^ 2 = x ^ 2 + y ^ 2, where "r" means the radius of the sphere.  This equation is the direct meaning of the sphere, which is the points equivocal from the midpoint. You can check this by selecting a point on the circle line and computing with the Pythagorean theorem.
But now we only use these things for drawing, so let's play with our sphere a little.
Let's stretch it along the "x" axis and make an ellipse, but how? Just change the "x" part of the equation a bit: r ^ 2 = (x / a) ^ 2 + y ^ 2
The same also works on the other axis.