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. A trapezium can also have parallel legs. The parallel sides can be horizontal, vertical or slanting.
The perpendicular distance between the parallel sides is called the altitude.
Examples:
Non-Examples:
| (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. |
| (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. |
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Types of Trapezoid
Trapezoid is of three types namely
1. Right trapezoid: It has a pair of right angles.
2. Isosceles trapezoid: It has equal length of non-parallel sides. In the image, sides, AD and BC are equal.
3. Scalene trapezoid: It neither has equal angles nor has equal sides.
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 = $\frac{BC+AD}{2}$ = $\frac{a+b}{2}$
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)
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.
Solved Examples on Trapezoid:
Example 1: Fill in the blanks.
- The trapezoid having non-parallel sides equal is known as ______________.
- _____________ trapezoid has a pair of adjacent angles equal to 90°.
- Neither the sides nor the angles of _______________ trapezoid are equal.
Solution:
- isosceles trapezoid
- Right
- scalene
Example 2: Find the length of median PQ of given trapezoid.
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.
Solution:
Perimeter = PQ + QR + RS + SP = (15 + 6 + 20 + 5) cm = 46 cm
Example 4: Find the area of a given 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
Trapezoid1 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 trapezoid and parallelogram?Trapezoid has 2 pairs of parallel sides, and parallelogram has 1 pair of parallel sides. Trapezoid has 1 pair of parallel sides and parallelogram has 2 pairs of parallel sides. Trapezoid has 2 sides and parallelogram has 4 sides. Trapezoid has 4 equal angles and parallelogram has all 4 unequal angles. CorrectIncorrect Correct answer is: Trapezoid has 1 pair of parallel sides and 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
Are all trapezoids quadrilaterals?
Since, trapezoids are closed figures with 4 sides so we can call them as quadrilaterals as well.
What is the difference between trapezoid and a trapezium?
By definition both trapezoid and trapezium are quadrilaterals with one pair of parallel sides. But, trapezoid is according to the US English and trapezium is according to the UK English.
Can a trapezoid have 4 right angles?
No, a trapezoid can have either 2 right angles or no right angles at all.
Are all rhombuses also trapezoids?
No, a trapezoid is a quadrilateral with only one pair of parallel sides whereas a rhombus has 2 pairs of parallel sides and all of them equal to each other.
Is trapezoid a parallelogram?
No, a trapezoid cannot be a parallelogram. Trapezoid has only one pair of parallel sides while in a parallelogram there are two pairs of parallel sides.