Pre-Algebra Demystified

SOLUTION

A¼pr^2
¼ 3 : 14 ð5in:Þ^2
¼ 3 : 14 25 in:^2
¼ 78 :5in:^2
The following suggestions will help you to convert between units. To
change:

 square feet to square inches, multiply by 144;

 square inches to square feet, divide by 144;

 square yards to square feet, multiply by 9;

 square feet to square yards, divide by 9.

EXAMPLE
Change 1728 square inches to square feet.

SOLUTION

1728 in.^2  144 ¼12 ft^2

EXAMPLE

Change 15 square yards to square feet.

SOLUTION

15 yd^2  9 ¼135 ft^2

PRACTICE

1. Find the area of a rectangle whose length is 123 yards and whose
   width is 53 yards.


2. Find the area of a square whose side is 53 inches.


3. Find the area of a triangle whose base is 16 inches and whose height is
   9 inches.


4. Find the area of a parallelogram whose base is 22 inches and whose
   height is 10 inches.


5. Find the area of a trapezoid whose bases are 32 feet and 44 feet and
   whose height is 20 feet.


6. Find the area of a circle whose radius is 14 inches. Usep¼ 3 :14.


7. Find the area of a circle whose diameter is 32 feet. Usep¼ 3 :14.


8. Change 12 square feet to square inches.

CHAPTER 9 Informal Geometry 175