If the center of the cone is in the plane, the intersection is a point, a straight line, or a pair of straight lines, depending on the angle of the axis of the cone. If the center of the cone is not in the plane, the intersection is a conic section. Let v be the angle of the cone, that is, the angle between the axis and one of the generating lines of the cone. You get a circle if the angle is 0 or Pi, an ellipse if the angle is between 0 and Pi-v (or between Pi+v and 2*Pi ), a parabola if the angle is Pi =/= v, and a hyperbola if the angle is within v of PiComponente Curricular::Educação Superior::Ciências Exatas e da Terra::Matemática