How do you find side #b# for a trapezoid?

1 Answer
Meave60
Oct 18, 2015

#b=(2A)/h-a#

Explanation:

#A=(h(a+b))/2# is the formula to find the area of a trapezoid (trapezium), where A is the area, h is the height, a is one parallel side, and b is the other parallel side..

Solving for side #b# implies that you know the area A, side #a#, and the height.

Multiply both sides times #2#.

#2A=h(a+b)#

Divide both sides by #h#.

#(2A)/h=a+b#

Subtract #a# from both sides.

#(2A)/h-a=b#

Switch sides.

#b=(2A)/h-a#

http://www.analyzemath.com/Geometry_calculators/trapezoid.html

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