Area of Isosceles Triangle Practice Problems & Solutions

Master calculating isosceles triangle area with step-by-step practice problems. Learn formulas, work through examples, and solve challenging exercises online.

📚Practice Finding the Area of Isosceles Triangles
  • Apply the base × height ÷ 2 formula to find isosceles triangle areas
  • Use the median-height property unique to isosceles triangles in calculations
  • Solve problems when only half the base length is given
  • Calculate areas of isosceles right triangles using the legs as base and height
  • Work through multi-step problems involving missing measurements
  • Master both basic and advanced isosceles triangle area applications

Understanding Area of Isosceles Triangles

Complete explanation with examples

Formula to calculate the area of an isosceles triangle

A1 - Area of the isosceles triangle

Height of the base × Base2=A \frac{Height~of~the~base~\times ~Base}{2}=A

Detailed explanation

Practice Area of Isosceles Triangles

Test your knowledge with 27 quizzes

Calculate the area of the following triangle:

666777AAABBBCCCEEE

Examples with solutions for Area of Isosceles Triangles

Step-by-step solutions included
Exercise #1

Complete the sentence:

To find the area of a right triangle, one must multiply ________________ by each other and divide by 2.

Step-by-Step Solution

To solve this problem, begin by identifying the elements involved in calculating the area of a right triangle. In a right triangle, the two sides that form the right angle are known as the legs. These legs act as the base and height of the triangle.

The formula for the area of a triangle is given by:

A=12×base×height A = \frac{1}{2} \times \text{base} \times \text{height}

In the case of a right triangle, the base and height are the two legs. Therefore, the process of finding the area involves multiplying the lengths of the two legs together and then dividing the product by 2.

Based on this analysis, the correct way to complete the sentence in the problem is:

To find the area of a right triangle, one must multiply the two legs by each other and divide by 2.

Answer:

the two legs

Exercise #2

Calculate the area of the following triangle:

444555AAABBBCCCEEE

Step-by-Step Solution

The formula for calculating the area of a triangle is:

(the side * the height from the side down to the base) /2

That is:

BC×AE2 \frac{BC\times AE}{2}

We insert the existing data as shown below:

4×52=202=10 \frac{4\times5}{2}=\frac{20}{2}=10

Answer:

10

Video Solution
Exercise #3

Calculate the area of the triangle using the data in the figure below.

101010222AAABBBCCC

Step-by-Step Solution

To solve the problem of finding the area of triangle ABC \triangle ABC , we follow these steps:

  • Step 1: Identify the given measurements.
  • Step 2: Use the appropriate formula for the area of a triangle.
  • Step 3: Calculate the area using these measurements.

Let's go through each step in detail:
Step 1: From the figure, the base AB=10 AB = 10 and height AC=2 AC = 2 .
Step 2: The formula for the area of a triangle is: Area=12×base×height \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} .
Step 3: Substituting the known values into the formula, we get:

Area=12×10×2=12×20=10 \text{Area} = \frac{1}{2} \times 10 \times 2 = \frac{1}{2} \times 20 = 10

Therefore, the area of triangle ABC \triangle ABC is 10.

Answer:

10

Video Solution
Exercise #4

Calculate the area of the triangle using the data in the figure below.

444777AAABBBCCC8.06

Step-by-Step Solution

To solve for the area of a triangle when the base and height are given, we'll use the formula:

Area=12×base×height \text{Area} = \frac{1}{2} \times \text{base} \times \text{height}

Given:

  • Base = 44 units

  • Height = 77 units

Apply the formula:

Area=12×4×7=12×28=14 \begin{aligned} \text{Area} &= \frac{1}{2} \times 4 \times 7 \\ &= \frac{1}{2} \times 28 \\ &= 14 \end{aligned}

Thus, the area of the triangle is 1414 square units.

Answer:

14

Video Solution
Exercise #5

Calculate the area of the following triangle:

4.54.54.5777AAABBBCCCEEE

Step-by-Step Solution

To find the area of the triangle, we will use the formula for the area of a triangle:

Area=12×base×height \text{Area} = \frac{1}{2} \times \text{base} \times \text{height}

From the problem:

  • The length of the base BC BC is given as 7 units.
  • The height from point A A perpendicular to the base BC BC is given as 4.5 units.

Substitute the given values into the area formula:

Area=12×7×4.5 \text{Area} = \frac{1}{2} \times 7 \times 4.5

Calculate the expression step-by-step:

Area=12×31.5 \text{Area} = \frac{1}{2} \times 31.5

Area=15.75 \text{Area} = 15.75

Therefore, the area of the triangle is 15.75 15.75 square units. This corresponds to the given choice: 15.75 15.75 .

Answer:

15.75

Video Solution

Frequently Asked Questions

What is the formula for finding the area of an isosceles triangle?

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The area of an isosceles triangle is calculated using the same formula as any triangle: Area = (base × height) ÷ 2. The key advantage is that in isosceles triangles, the height, median of the base, and angle bisector all coincide, making calculations easier.

How do you find the area of an isosceles triangle when given the median?

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In an isosceles triangle, the median of the base is also the height. Simply use the median as the height in the formula Area = (base × height) ÷ 2. If you're only given half the base, remember to double it to get the full base length.

What makes calculating isosceles triangle area different from other triangles?

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The unique property of isosceles triangles is that the height, median of the base, and angle bisector are the same line. This means you can use any of these three measurements as the height in your area calculation, providing more flexibility in solving problems.

How do you calculate the area of an isosceles right triangle?

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For an isosceles right triangle, the two equal sides (legs) form the right angle. Use these equal sides as both base and height in the formula: Area = (leg₁ × leg₂) ÷ 2. Since both legs are equal, it becomes Area = (leg²) ÷ 2.

What information do you need to find an isosceles triangle's area?

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You need two key measurements: 1) The length of the base, and 2) The height (or median/angle bisector). If you have an isosceles right triangle, you only need the length of one of the equal sides since both legs can serve as base and height.

Why is the height the same as the median in isosceles triangles?

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In isosceles triangles, the height drawn from the vertex angle to the base creates two congruent right triangles. This height line also bisects the base (making it the median) and bisects the vertex angle (making it the angle bisector). This triple property is unique to isosceles triangles.

What are common mistakes when calculating isosceles triangle area?

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Common mistakes include: 1) Using only half the base when the full base is needed, 2) Confusing which sides are equal in the triangle, 3) Not recognizing that the median equals the height, and 4) Forgetting to divide by 2 in the final calculation.

How do you solve isosceles triangle area problems step by step?

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Follow these steps: 1) Identify the base and height (or median/bisector), 2) If given half the base, double it for the full base length, 3) Apply the formula Area = (base × height) ÷ 2, 4) Calculate the multiplication first, then divide by 2, 5) Include proper units (cm², m², etc.) in your final answer.

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