Online Test Banks
Score higher
See Online Test Banks
Learning anything is easy
Browse Online Courses
Mobile Apps
Learning on the go
Explore Mobile Apps
Dummies Store
Shop for books and more
Start Shopping

How to Calculate the Area of a Trapezoid

You can use the right-triangle trick to find the area of a trapezoid. The following trapezoid TRAP looks like an isosceles trapezoid, doesn’t it? Don’t forget — looks can be deceiving.


You should be thinking, right triangles, right triangles, right triangles. So draw in two heights straight down from R and A as shown in the following figure.


You can see that QW, like RA, is 14. Then, because TP is 28, that leaves 28 – 14, or 14, for the sum of TQ and WP. Next, you can assign segment TQ a length of x, which gives segment WP a length of 14 – x. Now you’re all set to use — what else? — the Pythagorean Theorem. You have two unknowns, x and h, so to solve, you need two equations:


Now solve the system of equations. First, you subtract the second equation from the first, column by column:

  • Add a Comment
  • Print
  • Share
blog comments powered by Disqus

Inside Sweepstakes

Win $500. Easy.