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Section 4 Measurement
Notice it is not the length and the width that are being multiplied, but the length of one
side and the height. You may find it interesting to note that geometric shapes are often closely
related. If you were to cut the parallelogram below along the dotted line and then reassemble
it as shown, you would have created a rectangle. This is why the area of a parallelogram is
calculated by multiplying the length and the height.
Trapezoid
The trapezoid, like all the shapes studied so far, has four sides. Two of the sides are parallel,
but the other two sides are not parallel to each other. For this reason, a trapezoid is not as
symmetric or pleasing to look at as a parallelogram. Also, it does not appear in fabrication and
construction as often as the parallelogram.
Height
Perimeter of a Trapezoid
To calculate the perimeter of a trapezoid, add the four sides.
P = 54″ + 100″
″
+ 64″
″
+ 82″
″
P = 300″