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:

888101010AAABBBCCCEEE

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 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
Exercise #3

What is the area of the triangle in the drawing?

5557778.68.68.6

Step-by-Step Solution

First, we will identify the data points we need to be able to find the area of the triangle.

the formula for the area of the triangle: height*opposite side / 2

Since it is a right triangle, we know that the straight sides are actually also the heights between each other, that is, the side that measures 5 and the side that measures 7.

We multiply the legs and divide by 2

5×72=352=17.5 \frac{5\times7}{2}=\frac{35}{2}=17.5

Answer:

17.5

Video Solution
Exercise #4

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

666888AAABBBCCC

Step-by-Step Solution

To calculate the area of the triangle, we will follow these steps:

  • Identify the base, CB, as 6 units.
  • Identify the height, AC, as 8 units.
  • Apply the area formula for a triangle.

Now, let's work through these steps:

The triangle is a right triangle with base CB=6 CB = 6 units and height AC=8 AC = 8 units.

The area of a triangle is determined using the formula:

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

Substituting the known values, we have:

Area=12×6×8 \text{Area} = \frac{1}{2} \times 6 \times 8

Perform the multiplication and division:

Area=12×48=24 \text{Area} = \frac{1}{2} \times 48 = 24

Therefore, the area of the triangle is 24 24 square units.

Answer:

24

Video Solution
Exercise #5

Calculate the area of the triangle below, if possible.

7.67.67.6444

Step-by-Step Solution

To solve this problem, we begin by analyzing the given triangle in the diagram:

While the triangle graphic suggests some line segments labeled with the values "7.6" and "4", it does not confirm these as directly usable as pure base or height without additional proven inter-contextual relationships establishing perpendicularity or side/unit equivalences.

Without a clear base and perpendicular height value, we cannot apply the triangle's area formula Area=12×base×height \text{Area} = \frac{1}{2} \times \text{base} \times \text{height} effectively, nor do we have all side lengths for Heron's formula.

Therefore, due to insufficient information that specifically identifies necessary dimensions for area calculations such as clear height to a base or all sides' measures, the area of this triangle cannot be calculated.

The correct answer to the problem, based on insufficient explicit calculable details, is: It cannot be calculated.

Answer:

It 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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