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Discover the beauty and significance of conic sections, focusing on the geometry and properties of parabolas. Learn about translations, reflective properties, and the nature of conic sections in relation to gravitational fields. Delve into the equations, vertex forms, and characteristics of parabolas, including standard forms and focal properties.
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8.1 Demana, Waits, Foley, Kennedy Conic Sections and a New Look at Parabolas
What you’ll learn about • Conic Sections • Geometry of a Parabola • Translations of Parabolas • Reflective Property of a Parabola … and why Conic sections are the paths of nature: Any free-moving object in a gravitational field follows the path of a conic section.
Parabola A parabola is the set of all points in a plane equidistant from a particular line (the directrix) and a particular point (the focus) in the plane.
Parabolas with Vertex (0,0) • Standard equation x2 = 4pyy2 = 4px • Opens Upward or To the right or to the downward left • Focus (0, p) (p, 0) • Directrix y = –px = –p • Axis y-axis x-axis • Focal length pp • Focal width |4p| |4p|
Parabolas with Vertex (h,k) • Standard equation (x– h)2 = 4p(y – k)(y – k)2 = 4p(x – h) • Opens Upward or To the right or to the left downward • Focus (h, k + p) (h + p, k) • Directrix y = k-px = h-p • Axis x = h y = k • Focal length pp • Focal width |4p| |4p|