Trapezoids bridge the gap between ordinary quadrilaterals, 4-sided polygons, and parallelograms, quadrilaterals with two sets of parallel lines, by having just one set of parallel sides. This set, called the shape's bases, is integral in the calculation of a trapezoid's area. The shape's perimeter calculation isn't as rigid as its area calculation and does not require any distinction of the two bases. Finding a trapezoid's perimeter without knowing the bases therefore follows the same route as any other quadrilateral, with each side treated separately.
Instructions
-
-
1
Select one of the trapezoid's sides and measure it with your ruler. For an example, let the selected side measure 3 inches.
-
2
Measure each of the remaining sides clockwise. For this example, let the three remaining sides measure 3.5, 2.5 and 2 inches. Note that measuring the sides counterclockwise will also work.
-
-
3
Add together all four measurements to calculate the trapezoid's perimeter. Concluding this example, adding together 3, 3.5, 2.5 and 2 inches equals 11 inches.