👉 In geometry, a planispiral is a type of conic section that can be defined as a plane curve that is both a circle and a parabola. It is also known as a "star-shaped" or "cylinder-shaped" shape. A planispiral has two parallel curves (sides) and a single point at the center, which is called its focal point. The focal point of a planispiral is located on the plane that contains both of its