An Ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve. A circle curve are special cases of an ellipse, obtained when the cutting plane is orthogonal to the cone's axis. An Ellipse is closed curve and is the bounded case of the conic sections. The other two cases are parabola and hyperbola. It is also the simplest Lissajous curve, formed when the horizontal and vertical motions are sinusoids with the same frequency.