👉 In mathematics, a subinvolute is a curve that appears as an ellipse in the plane. Subinvolutes are also known as "subellipses" or "subelliptic curves". They are often used to model the shape of objects like gears and screwdrivers. A subinvolute can be defined as being tangent at one point but not at the same point twice, meaning that it is perpendicular to its own tangent line. It's important to note that a subinvolute