In this module students will,

• investigate
trigonometric ratios

•
determine the bolt circle diameter of a tire given it's chord length
and vice versa

• investigate
the connection between the circumference of a circle and PI using many
sided polygons

A problem often seen in automotive technology is determining the bolt
circle diameter of a tire.

The above diagram shows a typical bolt pattern consisting of 5
lug nuts. A lug nut is demonstrated by each of the small circles that
is around the bigger circle. Once either the chord length or the bolt
circle diameter is known, the other can be found.

To find either measurement, it is necessary to use
trigonometry. Trigonometry is the study of triangles and their
properties so the first part of this lesson will be to learn a little
about triangle ratios and their part in this problem.

If needed a short tutorial is provided if the student is
unfamiliar with Geometer's Sketchpad.

GSP - Tutorial.

Otherwise, Continue the Lesson
Worksheet 1.