How To Find The Perimeter Of A Trapezoid With A Missing Side

A trapezoid is a quadrilateral with two parallel sides. In geometry, you may be asked to find a missing side of a trapezoid, given the area and height. For example: a trapezoid has an area of 171 cm^2, a side of 10 cm and a height of 18 cm. How long is the missing side? Finding it takes some basic principles of geometry and a splash of algebra.

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Step 1

Substitute the information given in the question to the formula for finding the area of a trapezoid (A=.5height (base1+base2)). 171=(.5)*18(10+base2).

Step 2

Multiply out .5 by 18: 171= 9(10+base 2).

Step 3

Use the distributive property to multiple out the equation: 171= 90+9(base 2).

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Step 4

Use algebra to solve the remainder of the problem. Subtract 90 from both sides: 81=9(base2), then divide each side by 9. 9=base 2.

Cite This Article

MLA

Ellen, Stephanie. "How To Find The Perimeter Of A Trapezoid With A Missing Side" sciencing.com, https://www.sciencing.com/perimeter-trapezoid-missing-side-2393/. 24 April 2017.

APA

Ellen, Stephanie. (2017, April 24). How To Find The Perimeter Of A Trapezoid With A Missing Side. sciencing.com. Retrieved from https://www.sciencing.com/perimeter-trapezoid-missing-side-2393/

Chicago

Ellen, Stephanie. How To Find The Perimeter Of A Trapezoid With A Missing Side last modified March 24, 2022. https://www.sciencing.com/perimeter-trapezoid-missing-side-2393/

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