![]() ![]() Passes through the foci of the ellipse is the majorĪxis. In theĮllipse the sum of the two lines from any point of theĬurve to the two foci is constant that is: AG GB =ĪH HB and in the hyperbola the difference of theĬorresponding lines is constant. Parabola has one focus and one directrix. Two foci, and two corresponding directrixes, and the In the parabola equal to unity, and in the hyperbola In the ellipse this ratio is less than unity, So in the hyperbola, A is the focus andĬD the directrix when the ratio HA:HK is constant forĪll points of the curve and in the parabola, A is theįocus and CD the directrix when the ratio BA:BC isĬonstant. Note: Thus, in the ellipse FGHKLM, A is the focus and CD theĭirectrix, when the ratios FA:FE, GA:GD, MA:MC, etc.,Īre all equal. The distance of the same point from the directrix is Straight line called the directrix that the ratio of theĭistance between any point of the curve and the focus to ![]() (Geom.) A point so related to a conic section and certain (Opt.) A point in which the rays of light meet, afterīeing reflected or refracted, and at which the image isįormed as, the focus of a lens or mirror.Ģ. The Collaborative International Dictionary of English v.0.48:įocus \Fo"cus\ (f"ks), n. put (an image) into focus - Example: "Please focus the image we cannot enjoy the movie" become focussed or come into focus - Example: "The light focused" 5. bring into focus or alignment to converge or cause to converge of ideas or emotions 4. cause to converge on or toward a central point - Example: "Focus the light on this image" 3. direct one's attention on something - Example: "Please focus on your studies and not on your hobbies" 2. a fixed reference point on the concave side of a conic section VERB (5) 1. a point of convergence of light (or other radiation) or a point from which it diverges 7. special emphasis attached to something - Example: "the stress was more on accuracy than on speed" 6. a central point or locus of an infection in an organism - Example: "the focus of infection" 5. ![]() maximum clarity or distinctness of an idea - Example: "the controversy brought clearly into focus an important difference of opinion" 4. maximum clarity or distinctness of an image rendered by an optical system - Example: "in focus" - Example: "out of focus" 3. the concentration of attention or energy on something - Example: "the focus of activity shifted to molecular biology" - Example: "he had no direction in his life" 2. ![]()
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