Villarceau circles

Villarceau circles are a geometric concept associated with the study of toroidal shapes, specifically in relation to the geometry of a torus. These circles are defined by the intersection of a torus and a plane that cuts through it at a specific angle. When a torus is intersected by a plane not perpendicular to its central axis, the resulting intersection can yield various curves. If the angle of the plane is chosen correctly, the intersection forms a circle.