PreCalculus

• Circle is a set of all points on a plane which are equidistant from one another from a fixed point on a plane. The fixed point is called the center and the distance from the center to any points in the circle is called the radius.
• Ellipse is a set of all points in a plane, the sum of its distances from two fixed points is constant.
• The fixed point is called the foci of the ellipse. The line through them is sometimes called focal axis.
• The points where the ellipse crosses its focal axes is called vertices, while the line segment joining the two vertices is called the major axis.
• The chord of an ellipse passing through the center and perpendicular to the major axis is what we call minor axis. While the eccentricity of the ellipse is from 0 to 1 that is 0 < e < 1.