Click here to learn more about an isosceles trapezoid and even practice some exercises on the topic.
Right-angled trapezoid
A right trapezoid is a trapezoid that has 2 right angles, each equal to 90 degrees.
The properties of a right trapezoid are:
Exactly one pair of parallel sides
Two consecutive right angles (90°)
The leg connecting the right angles serves as the height
The other two angles are supplementary (sum to 180°)
One leg is perpendicular to both bases
No lines of symmetry (unless it's also isosceles)
Let's see this in the illustration:
How do you calculate the area of a right-angled trapezoid?
Just like calculating the area of a standard trapezoid, according to the formula:
2Sumofthebases⋅heighttothebase
here, the height is the perpendicular leg!
Do you know what the answer is?
Question 1
Look at the trapezoid in the figure.
Calculate its perimeter.
Incorrect
Correct Answer:
24.2
Question 2
What is the perimeter of the trapezoid in the figure?
Incorrect
Correct Answer:
16
Question 3
The trapezoid ABCD is shown below.
AB = 2.5 cm
DC = 4 cm
Height (h) = 6 cm
Calculate the area of the trapezoid.
Incorrect
Correct Answer:
\( 19\frac{1}{2} \)
Summary of Trapezoid Types
General Trapezoid: Basic quadrilateral with one pair of parallel sides
Isosceles Trapezoid: Legs are equal, has line of symmetry
Scalene Trapezoid: All sides different lengths, no symmetry
Right Trapezoid: Has two right angles
Acute Trapezoid: All angles less than 90°
Obtuse Trapezoid: Has at least one obtuse angle
Practice:
Given the following trapezoid:
It is known that angles A and B are each equal to 90 degrees. It is also known that the leg on which angles A and B rest is equal to 5 cm.
Additionally, the sum of the bases in the trapezoid is 15 and angle C is equal to 60.
Find the angle D.
Calculate the area of the trapezoid.
Solution
We know it is a right-angled isosceles trapezoid based on the given information where both angle A is 90 degrees and angle B is 90 degrees. Therefore, the sum of the other 2 angles is 180 degrees. It is given that C=60 degrees. Therefore, D=120 degrees 180−60=120 We substitute the data into the area formula for a right-angled trapezoid and get: 215.5∗5
Check your understanding
Question 1
Given: \( ∢C=2x \)
\( ∢A=120° \)
isosceles trapezoid.
Find x.
Incorrect
Correct Answer:
30°
Question 2
Given the trapezoid:
What is its perimeter?
Incorrect
Correct Answer:
32
Question 3
Look at the trapezoid in the diagram.
What is its perimeter?
Incorrect
Correct Answer:
36
Examples with solutions for Trapeze
Exercise #1
Do isosceles trapezoids have two pairs of parallel sides?
Step-by-Step Solution
To solve this problem, we'll follow these steps:
Step 1: Define the geometric properties of a trapezoid.
Step 2: Define the geometric properties of an isosceles trapezoid.
Step 3: Conclude whether an isosceles trapezoid has two pairs of parallel sides based on these definitions.
Now, let's work through each step:
Step 1: A trapezoid is defined as a quadrilateral with at least one pair of parallel sides.
Step 2: An isosceles trapezoid is a special type of trapezoid where the non-parallel sides (legs) are of equal length. Its defining feature is having exactly one pair of parallel sides, which is the same characteristic as a general trapezoid.
Step 3: Since the definition of a trapezoid inherently allows for only one pair of parallel sides, an isosceles trapezoid, as a type of trapezoid, cannot have two pairs of parallel sides. A quadrilateral with two pairs of parallel sides is typically designated as a parallelogram, not a trapezoid.
Therefore, the solution to the problem is that isosceles trapezoids do not have two pairs of parallel sides. No.
Answer
No
Exercise #2
Look at the trapezoid in the diagram.
What is its perimeter?
Video Solution
Step-by-Step Solution
In order to calculate the perimeter of the trapezoid we must add together the measurements of all of its sides:
7+10+7+12 =
36
And that's the solution!
Answer
36
Exercise #3
What is the area of the trapezoid in the figure?
Video Solution
Step-by-Step Solution
To solve this problem, we'll follow these steps:
Step 1: Identify the given information relevant to the trapezoid.
Step 2: Apply the appropriate formula for the area of a trapezoid.
Step 3: Perform the necessary calculations to find the area.
Now, let's work through each step:
Step 1: The problem gives us two bases, b1=6 cm and b2=12 cm, and a height h=4 cm.
Step 2: We'll use the formula for the area of a trapezoid:
A=21⋅(b1+b2)⋅h
Step 3: Substituting in the given values:
A=21⋅(6+12)⋅4=21⋅18⋅4=272=36 cm2
Therefore, the solution to the problem is 36 cm².
Answer
36 cm².
Exercise #4
What is the area of the trapezoid in the figure?
Video Solution
Step-by-Step Solution
To solve this problem, we'll compute the area of the trapezoid using the given dimensions and the area formula:
Step 1: Identify the given dimensions:
Base b1=10 cm
Base b2=6.5 cm
Height h=4 cm
Step 2: Use the trapezoid area formula:
The formula for the area of a trapezoid is A=21(b1+b2)h.
Step 3: Substitute the given values into the formula:
A=21(10+6.5)×4
Step 4: Calculate the area:
First, calculate the sum of the bases: 10+6.5=16.5.
Next, multiply by the height: 16.5×4=66.
Finally, divide by 2 to get the area: 266=33 cm².
Therefore, the area of the trapezoid is 33 cm².
Answer
33 cm².
Exercise #5
What is the area of the trapezoid in the diagram below?
Video Solution
Step-by-Step Solution
To determine the area of the trapezoid, we will follow these steps:
Step 1: Identify the provided dimensions of the trapezoid.
Step 2: Apply the formula for the area of a trapezoid.
Step 3: Perform the arithmetic to calculate the area.
Let's proceed through these steps:
Step 1: Identify the dimensions
The given dimensions from the diagram are:
Height h=3 cm.
One base b1=4 cm.
The other base b2=7 cm.
Step 2: Apply the area formula
To find the area A of the trapezoid, use the formula: A=21×(b1+b2)×h
Step 3: Calculation
Substituting the known values into the formula: A=21×(4+7)×3
Simplify the expression: A=21×11×3
Calculate the result: A=21×33=233=16.5 cm²
The area of the trapezoid is therefore 16.5 cm².
Given the choices, this corresponds to choice : 16.5 cm².
Therefore, the correct solution to the problem is 16.5 cm².