Figure 14-34.--Drawing a helix.
for calculating area and volume for that particular
Area is the extent of a surface bounded by two
figure.
dimensions, such as length and width. The unit of
measure showing area is the square, such as square
When values are enclosed in parentheses ( ),
inches, square feet, and square yards.
brackets [ ], or braces { }, they are grouped. Some
equations contain a group within a group. An example
Volume is the extent of an object bounded by three
of this is the formula for finding the area of a trapezium
dimensions, such as length, width, and height. The unit
where
of measure showing volume is the cube, such as cubic
inches or cubic feet.
A = 1/2[a(e + d) + bd + ce].
To find the area (A) of the rectangle shown in figure
In this formula you have parentheses and brackets.
14-35, you must multiply the length (L) by the width
Parentheses can be enclosed in braces, and braces can
(W) or A = LW. Since L = 8 inches and W = 5 inches,
A = 8 x 5 = 40 square inches.
To find the volume (V) of the cube shown in figure
14-36, you must multiply length (L) times width (W)
times height (H), or V = LWH. Since L = 8 inches,
W = 5 inches, and H = 7 inches, V = 8 5 7=280
cubic inches.
Many of the geometric figures you will be
concerned with are shown in figure 14-37. With each
figure is the formula and some examples of problems
Figure 14-35.--Two-dimensional view.
Figure 14-36.--Three-dimensional view.
14-19