Area of Isosceles Trapezoid Practice Problems with Solutions

Master calculating area of isosceles trapezoids with step-by-step practice problems. Learn formulas, properties, and midsegment concepts through guided examples.

📚Practice Calculating Isosceles Trapezoid Areas
  • Apply the trapezoid area formula: (base₁ + base₂) × height ÷ 2
  • Identify equal legs, base angles, and diagonals in isosceles trapezoids
  • Use midsegment properties to find missing base measurements
  • Calculate height when given area and base measurements
  • Solve multi-step problems involving perpendicular heights
  • Work with coordinate geometry and trapezoid vertices

Understanding Area of a Trapezoid

Complete explanation with examples

Area of an isosceles trapezoid

How to calculate the area of an isosceles trapezoid?

In order to calculate the area of an isosceles trapezoid, like every trapezoid's area, we need to multiply the height by the sum of the bases and divide by 22.
That is:

Diagram of a isosceles-angled trapezoid with the formula for calculating its area:  ( Base 1 + Base 2 ) × height (Base 1+Base 2)×height. The illustration highlights the two parallel bases, the height, and the application of the formula to find the area. Featured in a tutorial on calculating the area of trapezoids.


Important point – The midsegment of a trapezoid equals half the sum of the bases

Detailed explanation

Practice Area of a Trapezoid

Test your knowledge with 21 quizzes

Given the following trapezoid:

AAABBBCCCDDD7115

Calculate the area of the trapezoid ABCD.

Examples with solutions for Area of a Trapezoid

Step-by-step solutions included
Exercise #1

Given the following trapezoid:

AAABBBCCCDDD584

Calculate the area of the trapezoid ABCD.

Step-by-Step Solution

To solve this problem, we follow these steps:

  • Step 1: Identify the given dimensions of the trapezoid.
  • Step 2: Use the formula for the area of a trapezoid.
  • Step 3: Substitute the given values into the formula and calculate the area.

Now, let's work through these steps:

Step 1: We know from the problem that trapezoid ABCD has bases AB=5 AB = 5 and CD=8 CD = 8 , with a height of AD=4 AD = 4 .

Step 2: The formula for the area of a trapezoid is:
A=12×(b1+b2)×h A = \frac{1}{2} \times (b_1 + b_2) \times h

Step 3: Plugging in the values:
A=12×(5+8)×4=12×13×4=522=26 A = \frac{1}{2} \times (5 + 8) \times 4 = \frac{1}{2} \times 13 \times 4 = \frac{52}{2} = 26

Therefore, the area of the trapezoid ABCD is 26 26 .

Answer:

26

Video Solution
Exercise #2

Given the trapezoid:

999121212555AAABBBCCCDDDEEE

What is the area?

Step-by-Step Solution

Formula for the area of a trapezoid:

(base+base)2×altura \frac{(base+base)}{2}\times altura

We substitute the data into the formula and solve:

9+122×5=212×5=1052=52.5 \frac{9+12}{2}\times5=\frac{21}{2}\times5=\frac{105}{2}=52.5

Answer:

52.5

Video Solution
Exercise #3

Given the following trapezoid:

AAABBBCCCDDD683

Calculate the area of the trapezoid ABCD.

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Recall the formula for the area of a trapezoid.
  • Step 2: Substitute the given values into the formula.
  • Step 3: Calculate the area using arithmetic operations.

Let's work through each step:
Step 1: The formula for the area of a trapezoid is given by:
Area=12×(Base1+Base2)×Height \text{Area} = \frac{1}{2} \times (\text{Base}_1 + \text{Base}_2) \times \text{Height}
Step 2: Plug in the values: Base1=AB=6\text{Base}_1 = AB = 6, Base2=CD=8\text{Base}_2 = CD = 8, and the height AD=3AD = 3.
Area=12×(6+8)×3 \text{Area} = \frac{1}{2} \times (6 + 8) \times 3
Step 3: Perform the calculations:
Area=12×14×3=12×42=21 \text{Area} = \frac{1}{2} \times 14 \times 3 = \frac{1}{2} \times 42 = 21

Therefore, the area of trapezoid ABCDABCD is 2121.

Answer:

21

Video Solution
Exercise #4

The trapezoid ABCD is shown below.

AB = 2.5 cm

DC = 4 cm

Height (h) = 6 cm

Calculate the area of the trapezoid.

2.52.52.5444h=6h=6h=6AAABBBCCCDDD

Step-by-Step Solution

First, let's remind ourselves of the formula for the area of a trapezoid:

A=(Base + Base) h2 A=\frac{\left(Base\text{ }+\text{ Base}\right)\text{ h}}{2}

We substitute the given values into the formula:

(2.5+4)*6 =
6.5*6=
39/2 =
19.5

Answer:

1912 19\frac{1}{2}

Video Solution
Exercise #5

Given the following trapezoid:

AAABBBCCCDDD795

Calculate the area of the trapezoid ABCD.

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the lengths of the trapezoid's bases: AB=7 AB = 7 and CD=9 CD = 9 .
  • Step 2: Identify the height of the trapezoid: AD=5 AD = 5 .
  • Step 3: Apply the trapezoid area formula: A=12×(b1+b2)×h A = \frac{1}{2} \times (b_1 + b_2) \times h .
  • Step 4: Calculate the area using the values from Steps 1 and 2.

Now, let us work through each step:
Step 1: The length of base AB AB is (b1=7)(b_1 = 7) units, and the length of base CD CD is (b2=9)(b_2 = 9) units.
Step 2: The height AD AD is (h=5)(h = 5) units.

Step 3: Substitute the known values into the formula for the area of a trapezoid:
A=12×(7+9)×5 A = \frac{1}{2} \times (7 + 9) \times 5

Step 4: Calculate the results:
A=12×16×5=12×80=40 A = \frac{1}{2} \times 16 \times 5 = \frac{1}{2} \times 80 = 40

Therefore, the area of trapezoid ABCD is 40\mathbf{40} square units.

Answer:

40

Video Solution

Frequently Asked Questions

What is the formula for area of an isosceles trapezoid?

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The area formula is: Area = (base₁ + base₂) × height ÷ 2. This is the same formula used for all trapezoids, including isosceles trapezoids.

How do you find the height of an isosceles trapezoid?

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The height is the perpendicular distance between the parallel bases. You can identify it by looking for a 90° angle marker or by using given measurements and the Pythagorean theorem.

What makes an isosceles trapezoid different from a regular trapezoid?

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An isosceles trapezoid has three special properties: 1) Equal legs (non-parallel sides), 2) Equal base angles, and 3) Equal diagonals. These properties create symmetry that regular trapezoids don't have.

How does the midsegment help calculate trapezoid area?

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The midsegment equals half the sum of the bases. If you know the midsegment length, multiply by 2 to get the sum of bases, then use the area formula: midsegment × 2 × height ÷ 2.

What information do I need to find a trapezoid's area?

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You need: 1) The lengths of both parallel bases, 2) The height (perpendicular distance between bases). Alternatively, you can use the midsegment length instead of individual base lengths.

Can I use the same area formula for all types of trapezoids?

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Yes, the formula Area = (base₁ + base₂) × height ÷ 2 works for all trapezoids: isosceles, right-angled, and scalene trapezoids.

How do I solve trapezoid area problems with missing measurements?

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Use the given information systematically: 1) Identify what you know and what you need, 2) Apply trapezoid properties (like equal legs in isosceles), 3) Use geometry relationships to find missing values, 4) Substitute into the area formula.

What are common mistakes when calculating trapezoid area?

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Common errors include: forgetting to divide by 2, confusing legs with bases, using the wrong height measurement, and not recognizing when a segment is the midsegment rather than a base.

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