Conic sections were discovered by
Menaechmus, a Greek, at about 375 to 325 B.C.
He described them as those curves that could be formed by intersecting a cone with a plane.

A conic section is formed when a right circular double cone is sliced by a plane at different angles.
Notice the angles in which the plane intersects each cone.

The circle is formed when the plane sliced base of the cone.

The hyperbola is formed when the plane sliced base of the cone.

Applications of Hyperbolas
•The property of the hyperbola is the basis of several navigational systems used in order to locate objects.
•Hyperbolas are used in combat in sound ranging to locate the position of enemy guns by the sound of the firing of those guns.
•If a quantity varies inversely as another quantity, such as pressure and volume in Boyle’s Law for perfect gas (PV=k) then the graph is a hyperbola.
•Some comets move in hyperbolic orbits.

The parabola is formed when the plane that cuts of one of the cones.

Applications of Parabolas
The design of the headlight of a car is parabolic. The light bulb is located at the vertex of the parabolic mirror. The light beams will be reflected straight out from the headlight.
Satellite dishes capture the direct rays which are then reflected by the parabolic shape to the vertex of the dish.

The ellipse is formed when the plane intersecting

Applications of Ellipses
•If a person is positioned at one focus of a room that is shaped like an ellipse (such as the Oval Office), that person can hear the soft conversation of the other people positioned at the other focus of the ellipse. The reflective nature of the ellipse sends sound or light waves from one focus of the ellipse to the other.
•The Lithotriptor has made it possible to rid a person of a kidney stone. A strong “explosion” is emitted from an electrode positioned at one focus of an elliptical reflector. The shock wave from that electrode bounces off the reflector and centers in on the second focus of the ellipse where the kidney stone is positioned and breaks down the kidney stone.

1. Circle
2. Ellipse
3. Parabola
4. Hyperbola
1 2 3 4

• What defines it as a circle?

• What defines it as an ellipse

• What defines it as a parabola?

• What defines it as a hyperbola?

Symmetry – recall middle school
(Shapes)
• Horizontal
• Vertical
• Line y=x

Symmetry – High School
(Functions, equations, graphs)
• X-axis symmetry – it is reflected over the x axis
• Y-axis symmetry – it is reflected over the y axis
• Origin symmetry – it is reflected over both axis without changing shape

Circle
Ellipse

Parabola
Hyperbola

Circle
Ellipse

Parabola
Hyperbola