9.2. Parabolas http://www.ck12.org
9.2 Parabolas
Here you will define a parabola in terms of its directrix and focus, graph parabolas vertically and horizontally, and
use a new graphing form of the parabola equation.
When working with parabolas in the past you probably used vertex form and analyzed the graph by finding its roots
and intercepts. There is another way of defining a parabola that turns out to be more useful in the real world. One
of the many uses of parabolic shapes in the real world is satellite dishes. In these shapes it is vital to know where
the receptor point should be placed so that it can absorb all the signals being reflected from the dish.
Where should the receptor be located on a satellite dish that is four feet wide and nine inches deep?
Watch This
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/61845http://www.youtube.com/watch?v=k7wSPisQQYs James Sousa: Conic Sections: The Parabola part 1 of 2
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/61847http://www.youtube.com/watch?v=CKepZr52G6Y James Sousa: Conic Sections: The Parabola part 2 of 2
Guidance
The definition of a parabola is the collection of points equidistant from a point called the focus and a line called the
directrix.