Carpentry & Building Construction © 2004

Area of a Square and a Rectangle

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Area is the amount of space within a polygon or other flat figure. Area is measured in square units, as in square inches, square feet, and square yards. Carpenters use area measurements to estimate job costs, typically by the square foot. Also, the amount of material needed for roofing, flooring, and exterior walls may be calculated using area.

A square is a polygon with four right angles and four equal sides. To find the area of a square, multiply the length of one side times itself. The formula for the area of a square is A = s × s or A = s².

A rectangle is a polygon with four right angles and two sets of equal sides. To find the area of a rectangle, multiply the width times the length. The formula for the area of a rectangle is A=l × w. A shorter way of writing this is A = lw.

Practice Exercise

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Problem Exercises

1.		Find the area of a square whose side is 15''.
			A)	15 sq. in.
			B)	30 inches
			C)	60 sq. in.
			D)	225 sq. in.
2.		Find the area of a rectangle whose length is 9'' and whose width is 5''.
			A)	45''
			B)	45 sq. in.
			C)	28 sq. in.
			D)	14 sq. in.
3.		The area of flooring needed for a 10' × 12' room is
			A)	22 sq. ft.
			B)	100 sq. ft.
			C)	120 sq. ft.
			D)	120 ft.
4.		The area of a 9' × 15' wall to be covered by sheathing is
			A)	135 sq. ft.
			B)	96 sq. ft.
			C)	48 sq. ft.
			D)	24 sq. ft.
5.		A job requires building a 14' × 14' addition, whose floor area is
			A)	28 sq. ft.
			B)	56 sq. ft.
			C)	112 sq. ft.
			D)	196 sq. ft.