sxpe-xemmh R36-R44
11/22/05
4:33 PM
MAZER
Page 43
Finding Areas
The area of a figure is the amount of surface the figure covers.
Area is measured in square units, such as square meters (m2) or square
centimeters (cm2). Formulas for the areas of three common geometric figures
are shown below.
w
s
h
l
s
Area = (side
A = s2
b
Area = length width
A = lw
length)2
1
Area = base height
2
1
A = bh
2
Example
Each face of a halite crystal is a square like the one shown.
You can find the area of the square by using the steps below.
Write the formula for
the area of a square:
Substitute 3 mm for s:
Simplify:
3 mm
A = s2
= (3 mm)2
3 mm
= 9 mm2
MATH HANDBOOK
ANSWER The area of the square is 9 square millimeters.
Finding Volumes
The volume of a solid is the amount of space contained by the solid.
Volume is measured in cubic units, such as cubic meters (m3) or cubic centimeters
(cm3). The volume of a rectangular prism is given by the formula shown below.
h
w
Volume = length width height
V = lwh
l
Example
A topaz crystal is a rectangular prism like the one shown. You can find the volume of the
prism by using the steps below.
10 mm
Write the formula for the volume
of a rectangular prism:
Substitute dimensions:
Simplify:
V = lwh
12 mm
20 mm
= 20 mm 12 mm 10 mm
= 2400 mm3
ANSWER The volume of the rectangular prism is 2400 cubic millimeters.
Math Handbook R43
PDF