Chapter 4 Researching Designs 59
Step 1
Step 2
Step 3
Step 4
Boxes are sketched using these steps.
Figure 4-5.
Goodheart-Willcox Publisher
Step 1
Step 2
Step 3
Step 4
Step 5
Cylinders are sketched using these steps.
Figure 4-6. 
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Math
Calculations with Circles
Circles cannot be measured in the same way straight lines are measured. The
three key values when measuring circles are radius, diameter, and circumference.
The radius of a circle is half the width of the circle from its center. The radius is represented
in equations by r. The diameter of a circle is the full width across the center of the circle. In
equations, diameter is represented by d. To find the diameter of a circle, multiply the radius by 2.
d = 2 × r
Circumference is a measure of the perimeter of the circle. Circumference is repre-
sented as C in equations. Another value used in measuring circles is pi, represented as π.
Pi is a fixed number equal to about 3.14.
To find the circumference of a circle, multiply the diameter of the circle by pi. If you do
not know the diameter, multiply the radius by two, then multiply the product by pi.
C = d × π
C = 2 × r × π
Find the circumference of the following circles using the information given.
1. r = 2.5
2. d = 45
3. d = 350
4. r = 0.5
5. d = 1.5
6. d = 83
7. r = 0.03
8. r = 6.2