To do this part of the lesson, download this Geometer's Sketchpad file.

You will also need to use either of the 5 bolt pattern files.

**Use the 5 bolt GSP file to
answer the following.**

**STEP 1:** Measure the circumference of
the circle.

**STEP 2:** Now measure all
5 chord lengths. BC, CD, DE, EF, FB

**STEP 3:** Add the 5 chord
lengths together.

**STEP 4:** How close are
your answers to STEP 2 and 3.

**STEP 5:** Now find the Bolt
Circle Diameter for the 5 bolt pattern.

**Use the 20 bolt GSP file to
answer the following.**

**STEP 1:** Measure the
circumference of the circle.

**STEP 2:**
Now measure the chord length BC

**STEP 3:** Multiply your
answer to STEP 2 by 20 to find the sum of all the chord lengths
together.

**STEP 4:** How close are
your answers to STEP 2 and 3.

**STEP 5:** Compare your
answers for the 5 bolt and 20 bolt problems. In other words, which
answer is closer to the circumference you measured, the 5 bolt or the
20 bolt tire?

**STEP 6:** Can you make a
conclusion about the circumference of a circle and the sum of the chord
lengths as the number of lug nuts increases?

**STEP 7:** Now find the Bolt
Circle Diameter for the 20 bolt pattern.

**STEP 8:** Divide your
answer to STEP 1 by your answer to STEP 7. Does this number look
familiar? Explain.

To find the circumference of a circle, the formula is C =
(Pi)D, where D is the diameter of the circle (or in this case, the BOLT
CIRCLE DIAMETER) and Pi is the special number you found in STEP 8.