Conic Section Essay

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Project #2 - Conic Sections
Conic sections are the various gemetric figures created by the interection of a plane. They are among the oldest curves in history and is one of the oldest area of study for mathmaticians. conics were discovered by Menaechmus (c. 375 - 325 BC), a Greek pupil of Plato and Exodus. He was trying to solve the famous problem duplicating a cube. Euclid studied them and Appollonius reinforced and expanded previous results of conics into a book he named Conic Sections. It is a series of eight books with 487 propositions. He applied his findings to the study of planetary motion and it was used to advance the development of Greek astronomy. It is because of Appollonius that the name ellipse, parabola, and hyperbole were given to conics. Conics evolved even further during the Renaissance with Kepler’s law of planetary motion, Descarte on his work Geometry and Fermat’s coordinate geometry, and the beginning of projective geometry started by Desargues, La Hire, and Pascal. We can see conics in satellite dishes, sharpening pencils, automobile headlights, when a baseball is hit, telescopes, and much more. Physicians apply conics in treating kidney stones. Even, John Quincy Adams used conics to eaves drop on members of the house of representatives from his desk in the U.S. Capitol building.
Conic Sections are the improved curves produced by the intersection of a plane with a cone. For a plane perpendicular to the axis of the cone, a circle is produced. The definition of a cone includes the surface generated by a straight line that moves so that it always intersects the circumfrence of a given circle and passes through a given point not on the plane of the circle. The point, called the vertex of the cone, divides th...

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...t a polar equation for the ellipse. In defining the quality , our polar equation then becomes
;
since , we have  and thus


Because a , b , and f must be positive lengths, the quantity e must be positive; it is possible, though, for a to equal b (in which case, the ellipse becomes a circle), so that f = 0 , so e may also be zero. Since r , the distance from the focus at the origin to a point on the ellipse, must also be positive, we require that . No point on the ellipse is at the origin, so r ≠ 0 ⇒ e ≠ 1 . For an ellipse, then, 0 ≤ e < 1 .
This unification of the conic sections under one expression simplifies the proof that an object, subject to a force which varies with the inverse square of the distance from the agent of that force (such as gravity or the electric force of attraction or repulsion), will follow a path which is one of the conic sections.

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