EllipseEllipsi1.1 Oval, quadratic closed curve. 1.2 An ellipse is the intersection of a cone with an inclined plane 1.3 Ellipse area A = π x a x b a and b are minor and major axis 1.4 The orbit of each planet in the solar system is an ellipse In the time, the Sun, Moon and planets were assumed to have a perfect circular orbits. Johannes Kepler (1571 - 1630) rejected the idea of circular planetary orbits, and ended up the idea of their elliptical paths, as known nowadays 1.5 Five possible cross-section of the cone which is known for thousands of years. - point - circle - ellipse - hyperbola - parabola 1.6 The sum of distances from two poinst is equal to major axis. Points are two foci of the ellipse
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