Windows Live® Search Results

Focus (geometry) - Wikipedia, the free encyclopedia
In geometry, the foci (singular focus) are a pair of special points used in describing conic sections. The four types of conic sections are the circle, parabola, ellipse, and ...
Focus on Geometry
Customer Support. Phone: 1-800-848-9500 Fax: 1-877-260-2530 Address: 145 S. Mount Zion Road PO Box 2500 Lebanon, IN 46052
Focus (geometry) - MSN Encarta
Focus geometry, a fixed point in a plane that, in combination with a particular straight line or another point, specifies a type of curve called a

See all search results in
Windows Live® Search Results

Focus (geometry)

Encyclopedia Article

Focus (geometry), a fixed point in a plane that, in combination with a particular straight line or another point, specifies a type of curve called a conic section. Conic sections differ in the exact relationship between focus point and line (or point). A parabola, for instance, is the conic section consisting of the set of all points that are equally distant from a fixed focus point, F, and a line called the directrix:

An ellipse, by contrast, is the set of all points the sum of whose distances from a focus point, F₁, and another point, F₂ (also called a focus), is equal to a constant value: