Enrichment: Mechanical Constructions of Parabolas

These web-based activities were developed, during summer sessions from 1997 through 1999, by students at Mainland High School, located in Daytona Beach, FL. As part of Mainland's CCTT grant, the students were given permission by the book's publisher to convert the ancillary materials of the County's adopted Algebra 1 textbook (Glencoe Algebra 1 — ISBN: 9780028253282) into html format.

Enrichment
Mechanical Constructions of Parabolas

Another similar method of constructing parabolas is given in this lab activity.

A given line called the directrix and a point called the focus determine a parabola. Here is one way to construct the curve. Use a right triangle ABC (or a stiff piece of rectangular cardboard). Place one leg of the triangle on the given line d. Fasten one end of a string with length BC at the given point F and the other end to the triangle at point B. Put the tip of a pencil at point P and keep the string tight. The distance, FP + PB = BC. As you move the triangle along line d, the point of the pencil will trace out a parabola.
Directions: Draw the parabola determined by line d and point F.

Use your drawings to complete this conclusion. The greater the distance of point F from line d, _______________________________