Area
The area of an object is the number of square units that can be enclosed within the figure.
For example, the rectangle above encloses 6 square inches (6 in2).
Rectangle
A = lw
Triangle
A=
1
2
bh
Square
Parallelogram
A = s2
A = bh
Trapezoid
Circle
A=
1
2
( b1  b 2 ) h
A = r2
Example 1: Finding Area of a Parallelogram
.
Tip: Notice that the units of area
are always square units such as square
inches (in2), square feet (ft2), square
yards (yd2), square centimeters (cm2)
and so on.
Solution:
A = bh
Substitute b = 4 41 in. and h = 2 21 in
 17   5  85 2
in or 10 85 in 2
A = 4 41 in2 21 in =  in  in =
 4  2  8
The Academic Support Center at Daytona State College (Math 56 pg 1 of 2)
Example 2: Finding Area of a Trapezoid
Solution:
A = 21 ( b1  b 2 ) h
Substitute b1 = 16 yds, b2 = 10 yds, and h =
A = 21 (16 yds  10 yds)(3 yds) = 12 (26yds )(3yds ) = (13 yds)(3 yds) = 39 yds2
The area is 39 yds2
Example 3:
Finding Area of a Circle
Find the area of a circular fountain if the radius is 25 feet.
Use 3.14 for .
Solution:
A = r2
Substitute 3.14 for  and r = 25 ft
A = (3.14)(25 ft)2 = (3.14)(625 ft2) = 1962.5 ft2
The area of the fountain is 1962.5 ft2
The Academic Support Center at Daytona State College – (Math 56 pg 2 of 2)