Any curve made by the intersection of a plane and a right circular cone. The intersection can be an ellipse, hyperbola, circumference or a parabola depending on the angle of the planerelative to the cone.
* Open curve made by the intersection of a cone and a plane parallel to an element of the cone. It may be defined as a path of a point moving, so that itsdistance from a fixed line is equal to its distance of a fixed point. Its vertex is the point on the curve that is closest to the directrix (fixed line). The vertex and the focus (fixed point)determine a line, perpendicular to the directrix that is the axis of the parabola. The line through the focus parallel to the directrix is the latus rectum. Is symmetric about its axis, moves farther fromthe axis as the curve goes back in the direction away from the vertex.
* Is the length of any circle, the intersection of the sphere with any plane passing through itscenter.
* Is a curve formed by the intersection of a right circular cone and a plane. When the plane cuts both nappes of the cone, the intersection is a hyperbola. Because theplane is cutting two nappes, the curve it forms has two U-shaped branches opening in opposite directions.
* Is defined by two points, each called a focus. (F1, F2 above). If youtake any point on the ellipse, the sum of the distances to the focus points is constant. In the figure above, drag the point on the ellipse around and see that while the distances to the focus pointsvary, their sum is constant. The size of the ellipse is determined by the sum of these two distances. The sum of these distances is equal to the length of the major axis (the longest diameter of theellipse)
* Straight Line
* Basic element of Euclidean geometry. Euclid defined a line as an interval between two points and claimed it could be extended indefinitely in either direction....