A trapezoid is a four-sided shape with two parallel sides, one longer than the other, and two lines that connect those two sides, coming from the Greek for ‘table’. As such, it has very little use in design, as people tend to design things with three sides or two sets of parallel sides, thus making rectangular objects and structures.

This said, one can observe such a shape during the constructions of bridges, in particular in their trusses. One can see a trapezoid in the form of the truss, with a shorter straight top side to complement the longer bottom side which forms the road on which vehicles can travel; connecting the top and bottom are two slanted sides and as such one can see a trapezoid. There are several types of truss bridge, not all of which are directly trapezoidal, though those that are include the Pratt truss (invented by the Pratt Brothers in 1844), the Whipple truss (also known as the double-intersection truss) and the Warren truss.

Though less common when used for cars, The Whipple truss gained immediate popularity with the transcontinental railroads as it was stronger and more rigid than the Pratt. They were usually built where the span required was longer than was practical with a Pratt truss. However, further developments of the subdivided variations of the Pratt led to the decline of the Whipple truss.

Aside from bridges, roofs of houses with one set of parallel sides are a much more common example, and can also be seen in large furnishings, such as doors and windows where the base is wider than its top, and thus need to be tapered towards the latter with diagonal fortifications. Some note that this was common in Egypt. Be on the lookout for more examples, such as in pencil cases.

This said, one can observe such a shape during the constructions of bridges, in particular in their trusses. One can see a trapezoid in the form of the truss, with a shorter straight top side to complement the longer bottom side which forms the road on which vehicles can travel; connecting the top and bottom are two slanted sides and as such one can see a trapezoid. There are several types of truss bridge, not all of which are directly trapezoidal, though those that are include the Pratt truss (invented by the Pratt Brothers in 1844), the Whipple truss (also known as the double-intersection truss) and the Warren truss.

Though less common when used for cars, The Whipple truss gained immediate popularity with the transcontinental railroads as it was stronger and more rigid than the Pratt. They were usually built where the span required was longer than was practical with a Pratt truss. However, further developments of the subdivided variations of the Pratt led to the decline of the Whipple truss.

Aside from bridges, roofs of houses with one set of parallel sides are a much more common example, and can also be seen in large furnishings, such as doors and windows where the base is wider than its top, and thus need to be tapered towards the latter with diagonal fortifications. Some note that this was common in Egypt. Be on the lookout for more examples, such as in pencil cases.