Apollonius of Perga facts for kids
Apollonius of Perga (Greek: Ἀπολλώνιος ὁ Περγαῖος; Latin: Apollonius Pergaeus; late 3rd – early 2nd centuries BC) was a Greek geometer and astronomer known for his theories on the topic of conic sections. Beginning from the theories of Euclid and Archimedes on the topic, he brought them to the state they were in just before the invention of analytic geometry. His definitions of the terms ellipse, parabola, and hyperbola are the ones in use today.
Apollonius worked on many other topics, including astronomy. Most of the work has not survived except in fragmentary references in other authors. His hypothesis of eccentric orbits to explain the apparently aberrant motion of the planets, commonly believed until the Middle Ages, was superseded during the Renaissance.
Images for kids

The animated figure depicts the method of "application of areas" to express the mathematical relationship that characterizes a parabola. The upper left corner of the changing rectangle on the left side and the upper right corner on the right side is "any point on the section." The animation has it following the section. The orange square at the top is "the square on the distance from the point to the diameter; i.e., a square of the ordinate. In Apollonius, the orientation is horizontal rather than the vertical shown here. Here it is the square of the abscissa. Regardless of orientation, the equation is the same, names changed. The blue rectangle on the outside is the rectangle on the other coordinate and the distance p. In algebra, x2 = py, one form of the equation for a parabola. If the outer rectangle exceeds py in area, the section must be a hyperbola; if it is less, an ellipse.