You need to also count "points at infinity" in the "projective" plane. So the "projectivized" equations are actually X^2 + Y^2 = 1Z, and X^2 + Y^2 = 4Z. The int

You need to also count "points at infinity" in the "projective" plane. So the "projectivized" equations are actually X^2 + Y^2 = 1Z, and X^2 + Y^2 = 4Z. The intuition is similar to how 2 parallel lines will meet at the horizion (infinity).