5. Finding area of trapezoids

• A trapezoid is a 4-sided polygon with exactly one pair of parallel sides. Rectangles and parallelograms are not trapezoids, since both pairs of opposite sides of a rectangle or parallelogram are parallel.

• The bases of a trapezoid are its parallel sides. The height of a trapezoid is the distance between the bases, measured along a line that is perpendicular to both bases.

• The area formula for a trapezoid is similar to the area formula for a rectangle or parallelogram. Instead of multiplying height by base to figure out area, multiply the trapezoid's height by the average of its two bases. In other words

Trapezoid Area = h(b1+b2)/2


• For each trapezoid in the figure at the right, count squares to find

• Then use A = h(b1+b2)/2 to figure out the area of the trapezoid.
• Type the values of b1 ,b1 ,h, and A into the yellow boxes by first clicking to the right of the equals sign.
• Click on 'Check your work' at any time.
• When your score is perfect, click on 'New Quiz' to get new trapezoids.