Advanced Waterworks Mathematics, 2019a

Trapezoids
Trapezoids are four-sided shapes with one set of parallel sides. Aqueducts are commonly a
trapezoid in cross section with a parallel top and bottom called bases. Aqueducts have narrow
flat bottoms and wider flat tops at the water level. Aqueducts are typically miles and miles of
trapezoidal shaped concrete channels. They have flat narrow bottoms that slope up to wider
distances at the top.
Figure 2.7: Public Domain from U.S.G.S. of California Aqueduct through the Central Valley transporting water from
Northern California to Southern California 7
In order to calculate the varying distances across a trapezoid, add the distance (width, b2)
across the bottom to the distance (width, b1) across the top and divide by 2. This gives the
average width. Then multiply the average width by the height or depth of the trapezoid to
calculate the area.
Figure 2.8 8
Area of a Trapezoid =
b b
2
1 2
H
7
Image by the USGS is in the public domain
8
Image by Marilyn Hightower is licensed under CC BY 4.0
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