To do this part of the lesson,
continue using the Bolt_Circle_1.gsp file you downloaded in the
DATA: 12 cm bolt circle
diameter - 5 bolt pattern
STEP 1: Look at this
The distance from the lug nut to the center of the circle is
called the HYPOTENUSE of the triangle EAX. The HYPOTENUSE is the side
opposite the right angle of the triangle.
Measure the length of the HYPOTENUSE
STEP 2: In
this situation, it is also half the measure of the bolt circle
To find the chord length, we need to find the measure of a.
Now, measure <EAX (or <A)?
Also, measure <DAX (or <A)?
What do you notice about these two angles?
STEP 3: We now know the
measure of the hypotenuse, and the measure of <A. This is all the
information we need to find the chord length. However, we do have to do
one more thing.
Highlight the measure of <A. Under the menu Measure,
select Calculate.... Find the SIN of <A
STEP 4: Now
multiply the SIN of <A and the HYPOTENUSE.
STEP 5: Measure the
distance from E to X.
STEP 6: What do you
notice about your answer to STEP 4 and 5?
STEP 7: How can you
find the chord length from E to D based on your answer to STEP 4.