Perimeter of a Trapezoid
Sum of all four sides of a trapezoid.
Formula
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Example
Sides 5, 6, 7, 8: P = 5+6+7+8 = 26 units.
How it works
The perimeter of a trapezoid is the total distance around its outside edge, so you find it by adding the lengths of all four sides. Even though a trapezoid has only one pair of parallel sides, every side still contributes to the boundary, which is why the formula is just a sum. This works for any trapezoid as long as a, b, c, and d represent the lengths of its four sides.
When to use it
Use this formula when you need the outside length of a trapezoid-shaped object, such as in fencing, framing, edging, or geometry problems. It is also useful whenever a diagram gives all four side lengths and asks for the total boundary length.
Worked example, step by step
Suppose a trapezoid has side lengths 4 cm, 9 cm, 5 cm, and 6 cm. P = a + b + c + d P = 4 + 9 + 5 + 6 P = 24 So, the perimeter is 24 cm.
Common mistakes to avoid
- Forgetting to include all four sides and adding only the parallel sides
- Using the wrong units or leaving off the unit in the final answer
- Confusing perimeter with area and trying to multiply side lengths
Did You Know?
A trapezoid is the only quadrilateral defined by having exactly one pair of parallel sides.
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