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 triangle below, if possible.

7.67.67.6444

Examples with solutions for Area of Isosceles Triangles

Step-by-step solutions included
Exercise #1

Calculate the area of the right triangle below:

101010666888AAACCCBBB

Step-by-Step Solution

Due to the fact that AB is perpendicular to BC and forms a 90-degree angle,

it can be argued that AB is the height of the triangle.

Hence we can calculate the area as follows:

AB×BC2=8×62=482=24 \frac{AB\times BC}{2}=\frac{8\times6}{2}=\frac{48}{2}=24

Answer:

24 cm²

Video Solution
Exercise #2

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

121212888999AAABBBCCCDDD

Step-by-Step Solution

First, let's remember the formula for the area of a triangle:

(the side * the height that descends to the side) /2

 

In the question, we have three pieces of data, but one of them is redundant!

We only have one height, the line that forms a 90-degree angle - AD,

The side to which the height descends is CB,

Therefore, we can use them in our calculation:

CB×AD2 \frac{CB\times AD}{2}

8×92=722=36 \frac{8\times9}{2}=\frac{72}{2}=36

Answer:

36 cm²

Video Solution
Exercise #3

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 #4

Calculate the area of the following triangle:

666777AAABBBCCCEEE

Step-by-Step Solution

The formula for the area of a triangle is

A=hbase2 A = \frac{h\cdot base}{2}

Let's insert the available data into the formula:

(7*6)/2 =

42/2 =

21

Answer:

21

Video Solution
Exercise #5

Calculate the area of the triangle below, if possible.

8.58.58.5777

Step-by-Step Solution

The formula to calculate the area of a triangle is:

(side * height corresponding to the side) / 2

Note that in the triangle provided to us, we have the length of the side but not the height.

That is, we do not have enough data to perform the calculation.

Answer:

Cannot be calculated

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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