1, parabola: a parabola refers to the trajectory in a plane to a point whose distance from a fixed point to a fixed line is equal to L. There are many representations of parabola, such as parameter representation and standard equation representation. Parabola plays an important role in geometric optics and mechanics. Parabola is also a kind of conic curve, that is, the curve obtained by the intersection of a conic surface and a plane parallel to the generatrix. Parabola can also be regarded as quadratic function image under proper coordinate transformation;

2. Circle: A circle is a geometric figure, which refers to the set of all points on a plane, and the distance between these points and a fixed point is constant. This given point is called the center of the circle. The distance as a fixed value is called the radius of a circle. When a line segment rotates once around one of its endpoints on a plane, the trajectory of its other endpoint is a circle. According to the definition, compasses are usually used to draw circles;

3. Hyperbola: Hyperbola is defined as the locus of a point whose distance difference from one point to two fixed points is constant. This fixed distance difference is twice that of A, where A is the distance from the center of hyperbola to the vertex of the nearest branch of hyperbola. A is also called the real semi-axis of hyperbola. The focal point is located on the through axis, and the middle point is called the center, which is generally located at the origin.