Conic sections are shapes formed by the intersection of a plane with a right circular cone. There are four basic conic sections: ellipses are formed when the plane intersects the cone at an angle greater than the vertex angle; circles are formed when the plane is perpendicular to the axis of the cone; parabolas are formed when the plane intersects at an angle equal to the vertex angle; and hyperbolas are formed when the plane intersects at an angle less than the vertex angle. Degenerate conics are also possible if the plane passes through the vertex of the cone, forming a point, line, or intersecting lines instead of the standard conic sections.