

Units of Area A square foot measures 1 foot by 1 foot. It also measures 12 inches by 12 inches. Therefore, one square foot also equals 144 square inches (that is, 12 x 12 = 144). To convert square feet to square inches, multiply by 144. To convert square inches to square feet, divide by 144. A square yard measures 1 yard by 1 yard. It also measures 3 feet by 3 feet. Therefore, one square yard also equals 9 square feet (that is, 3 x 3 = 9). To convert square yards to square feet, multiply by 9. To convert square feet to square yards, divide by 9. Refer to Figure 137, Applied Mathematics Formula Sheet, at the end of the chapter for a comparison of different units of area. Figure 123 summarizes the formulas for computing the area of twodimensional solids.
Computing Volume of ThreeDimensional Solids Threedimensional solids have length, width, and height. There are many threedimensional solids, but the most common are rectangular solids, cubes, cylinders, spheres, and cones. Volume is the amount of space within a solid. Volume is expressed in cubic units. Cubic inches or cubic centimeters are used for small spaces and cubic feet or cubic meters for larger spaces. Rectangular Solid rectangleshaped sides. [Figure 124] The volume is the number of cubic units within the rectangular solid. The formula for the volume of a rectangular solid is: Volume = Length x Width x Height = L x W x H In Figure 124, the rectangular solid is 3 feet by 2 feet by 2 feet. The volume of the solid in Figure 124 is = 3 ft x 2 ft x 2 ft = 12 cubic feet. Example: A rectangular baggage compartment measures 5 feet 6 inches in length, 3 feet 4 inches in width, and 2 feet 3 inches in height. How many cubic feet of baggage will it hold? First, substitute the known values into the formula.

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