A trapezoid is a four-sided figure that has one pair of parallel lines and one pair of non-parallel lines. A 3-D trapezoid adds depth to this shape. Calculating the volume of a 3-D trapezoid is ideal for calculating the volume of a pool that slopes from the shallow end to the deep end. To calculate the volume you need to know the length, width, minimum height and maximum height of the trapezoid.

- Skill level:
- Moderate

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## Instructions

- 1
Calculate the area of the base of the trapezoid by multiplying the length times the width. For example, if you had a swimming pool that was 25 feet long and 20 feet wide, the base would be 500 square feet.

- 2
Add the minimum height of the trapezoid to the maximum height of the trapezoid. For example, if your pool had a minimum depth of 5 feet and a maximum depth of 9 feet, the average would be 7 feet.

- 3
Multiply the depth of the pool times the area from Step 1 to calculate the volume of the 3-D trapezoid. In this example, the area of the pool would be equal to 7 times 500, or 3,500 cubic feet.