COLLEGE ALGEBRA: AN INVESTIGATIVE APPROACH

by

S. Kastberg & T. Barron


GRAPHING QUADRATIC FUNCTIONS

INVESTIGATION 1: Constructing Parabolas given the focus and the directrix


A parabola can be defined as the set of all points in the plane equidistant from a given point (called the focus) and a given line (called the directrix). In this investigation you will be asked to examine a parabola constructed using this definition.

Click HERE to examine a parabola constructed in Geometer's Sketch Pad using the above definition.

Explain how the parabola is formed.

Develop a set of instructions from which a point on a parabola could be constructed using a ruler and compass.

What is the vertex of this parabola?

What is the relationship between the vertex, focus and the directrix?


Return