Answer:

A = 1/2 x (5 + 7) x 3
A = 1/2 x (12) x 3
A = 18 square cm

Summary:

• A trapezoid consists of two parallel bases and two non-parallel sides.
• The distance between the bases is the height.
• Bases can be either the top and bottom or the left and right sides of a trapezoid.
• The formula for finding the area of a trapezoid is:

On the Web: Try the problems listed on this page. You'll know right away if you get them right.

Extra credit: (You need graph paper.) Draw a trapezoid whose vertices in a coordinate plane are (5, 10), (10, 5), (9, 10) and (3, 5). What is its area in units? (You don't need a ruler for this problem!)