| In continuation of the "Why Study Math" series of | | | | circular cone. (To get a double-napped cone, add |
| articles, here we look at another conic section: the | | | | another cone on top, right-side up, balanced at the |
| ellipse. The four conic sections, in order from | | | | point.) To get the circle, take an imaginary plane |
| most popularly known to least, are the circle, the | | | | (picture a piece of paper) and intersect the cone |
| ellipse, the parabola, and the hyperbola. | | | | at a right angle to the base. The plane has just |
| Remember that these shapes can all be obtained | | | | cut out a circle on the cone. Similarly, to get the |
| by slicing a right circular double-napped cone with | | | | ellipse tilt the plane slightly up or down and |
| a plane. As a visual exercise, picture an ice cream | | | | intersect it with the cone. What you have then is |
| cone—without the ice cream—upside down | | | | an elongated circle, or ellipse. |
| standing on a table. This is a single-napped right | | | | |