Trapezoid – Definition, Types, Properties, Examples, FAQs

Home » Math Vocabluary » Trapezoid – Definition, Types, Properties, Examples, FAQs

What is Trapezoid?

A trapezoid, also known as a trapezium, is a flat closed shape having 4 straight sides, with one pair of parallel sides. 

The parallel sides of a trapezium are known as the bases, and its non-parallel sides are called legs. The parallel sides can be horizontal, vertical or slanting. 

The perpendicular distance between the parallel sides is called the altitude. 

parts of trapezoid

Examples:

examples of trapezoid

Non-Examples:

six sided figure
three sided figure with no parallel sides
(A) It is not a trapezoid because it is a 6-sided figure.(B) It is not a trapezoid because it is a 3-sided figure with no parallel sides.
curved figure
pair of parallel sides
(C) It is not a trapezoid because it is a curved figure.(D) It is not a trapezoid because it has rounded corners and 2 pairs of parallel sides.

Trapezoid Definition

  • Exclusive Definition: A trapezoid is a quadrilateral with exactly one pair of parallel sides. (By this definition, a parallelogram is not a trapezoid since it has two pairs of parallel sides.)
  • Inclusive Definition: A trapezoid is a quadrilateral with at least one pair of parallel sides. (By this definition, a parallelogram becomes a special type of trapezoid, a trapezoid with two pairs of parallel sides.)

Types of Trapezoid

Trapezoid is of three types namely

1. Right trapezoid: It has a pair of right angles.

right trapezoid

2. Isosceles trapezoid: It has equal length of non-parallel sides. In the image, sides, AD and BC are equal.

isosceles trapezoid

3. Scalene trapezoid: It neither has equal angles nor has equal sides.

scalene trapezoid

Median of Trapezoid

A median of a trapezoid is the line segment joining the midpoints of the two non-parallel sides of a trapezoid.

The median of a trapezoid is parallel to the set of parallel lines.

Median of trapezoid

Median = $\frac{BC+AD}{2}$ = $\frac{a+b}{2}$

Properties of a Trapezoid

  • The bases are parallel to each other.
  • The median is parallel to both the bases and its length will be the average of the length of the bases.
  • Sum of all the angles in a trapezoid is equal to 360°.
  • The sum of the angles on the same side is equal to 180°.

Area of Trapezoid

Area of a trapezoid = $\frac{1}{2}$ × (sum of parallel sides) × (distance between them)

Area of trapezoid

Let ABCD be a trapezoid in which AB is parallel to DC and let h be the height.

Area = $\left\{\frac{1}{2}\times (AB + BC)\times h \right\}$

= $\left\{\frac{1}{2}\times (a + b)\times h \right\}$

Perimeter of Trapezoid

The perimeter of a trapezoid is the sum of all its sides.

Therefore, for the trapezoid shown above with sides AB, BC, CD and DA, the perimeter can be written as

Perimeter = AB + BC + CD + DA

Real Life Examples

We can find trapezoids in many real-life objects For example a lamp, popcorn box, handbag, and so on.

perimeter of trapezoid

Solved Examples on Trapezoid

Example 1: Fill in the blanks.

  1. The trapezoid having non-parallel sides equal is known as ______________.
  2. _____________ trapezoid has a pair of adjacent angles equal to 90°.
  3. Neither the sides nor the angles of _______________ trapezoid are equal.

Solution:

  1. isosceles trapezoid
  2. Right
  3. scalene

Example 2: Find the length of median PQ of given trapezoid.

length of median

Solution:

Median = $\frac{1}{2}\times (\text{sum of the basis}) = \frac{AD + BC}{2} = \frac{8 + 30}{2} cm = 19 cm$

Example 3: Find the perimeter of a given trapezoid.

perimeter of trapezoid example

Solution:

Perimeter = PQ + QR + RS + SP = (15 + 6 + 20 + 5) cm = 46 cm

Example 4: Find the area of a given trapezoid.

area of a trapezoid

Solution:

Area = $\frac{1}{2}\times (\text{sum of parallel sides})\times (\text{altitude})$

= $\frac{1}{2}\times (7 + 11)\times 6$ sq.cm

= $\frac{1}{2}\times 18\times 6 sq.cm$

= 54 sq.cm

Practice Problems On Trapezoid

Trapezoid

Attend this Quiz & Test your knowledge.

1

The altitude refers to what measurement of a trapezoid?

Heigh
Width
Angle
Diagonal
CorrectIncorrect
Correct answer is: Heigh
The height of the trapezoid is referred to as it's altitude.
2

How many right angles are there in the right trapezoid?

One
Two
Three
Four
CorrectIncorrect
Correct answer is: Two
A right trapezoid is a trapezium with a pair of right angles.
3

What is the difference between a trapezoid and a parallelogram?

A trapezoid has 2 pairs of parallel sides, and a parallelogram has 1 pair of parallel sides.
A trapezoid has 1 pair of parallel sides and a parallelogram has 2 pairs of parallel sides.
A trapezoid has 2 sides and a parallelogram has 4 sides.
A trapezoid has 4 equal angles, and a parallelogram has all 4 unequal angles.
CorrectIncorrect
Correct answer is: A trapezoid has 1 pair of parallel sides and a parallelogram has 2 pairs of parallel sides.
Trapezoid has 1 pair of parallel sides and parallelogram has 2 pairs of parallel sides.
Both trapezoid and parallelogram are quadrilaterals. The difference lies in the number of parallel sides they have.
4

What do we call sides which are not parallel in a trapezoid?

Diagonals of trapezoid
Bases of trapezoid
Legs of trapezoid
Altitudes of trapezoid
CorrectIncorrect
Correct answer is: Legs of trapezoid
The two parallel sides of the trapezoid are referred to as the bases of the trapezoid; the other two sides are called the legs of the trapezoid.

Frequently Asked Questions On Trapezoid

Trapezoids are closed figures with 4 sides. So we can call them quadrilaterals.

What we call a trapezoid in the US is a trapezium in the UK. By the exclusive definition, both trapezoid (US) and trapezium (UK) are quadrilaterals with one pair of parallel sides. (Also, note that a quadrilateral with no parallel sides is called a trapezium in the US and a trapezoid in the UK.)

No, a trapezoid can have either 2 right angles or no right angles at all.

  • Under the exclusive definition, a trapezoid is a quadrilateral with only one pair of parallel sides. Thus, a rhombus which has two pairs of parallel sides, is not a trapezoid.
  • Under the inclusive definition, a trapezoid has at least one pair of parallel sides. By this definition, a rhombus is a trapezoid.
  • By the exclusive definition, a trapezoid is not a parallelogram. Under this definition, a trapezoid has exactly one pair of parallel sides, while in a parallelogram, there are two pairs of parallel sides.
  • By the inclusive definition, a trapezoid has at least one pair of parallel sides. Thus, when a trapezoid has two parallel sides, it becomes a parallelogram.