Copyright by The Goodheart-Willcox Co., Inc.
155
Key Terms
Unit 17
Four-Sided Measure
area
parallelogram
perimeter
rectangle
square
square units
trapezoid
Introduction
The products that you will work on in the shop or at the job site are made up of regular
geometric shapes that can be measured. Products, such as frames, braces, drums, bins, hoppers,
chutes, and tanks, are examples of such items. In this unit, you will learn to calculate the
perimeter and area of the most common four-sided shapes found in industry. The perimeter is
the distance around a shape. The area is the surface measure of a shape.
Square
A square is a shape having four sides, with its opposite sides being parallel, all sides being
the same length, and all its angles being 90°.
Perimeter of a Square
To calculate the perimeter of a square, add the four sides.
P = 7″ + 7″ + 7″ + 7″
P = 28″
90° angle
Parallel
sides
Parallel
sides
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