Triangle Perimeter Practice Problems & Solutions

Master triangle perimeter calculations with step-by-step practice problems. Learn formulas for equilateral, isosceles, and scalene triangles with interactive exercises.

📚Practice Calculating Triangle Perimeters
  • Calculate perimeter by adding all three sides of any triangle
  • Apply perimeter formulas for equilateral triangles using one side length
  • Solve isosceles triangle perimeter problems with base and equal sides
  • Work with different units of measurement (mm, cm, meters)
  • Find missing side lengths when perimeter is given
  • Apply triangle perimeter concepts to real-world measurement problems

Understanding Perimeter

Complete explanation with examples

What is the perimeter?

The perimeter indicates the distance we will walk if we start from a certain point, complete a full lap, and return exactly to the starting point.
For example, if we are asked what the perimeter of the waist is, we will take a tape measure and measure the perimeter from a certain point until completing a full lap and returning to the same point from which we started the measurement.
It works exactly the same way in mathematics. The perimeter of any shape is the distance from a specific point back to it after having completely surrounded it.
If this is our figure:

What is the perimeter

Its perimeter will be the distance we cover if we travel along its line from a certain point, and return to it after making a full lap. Imagine that you are surrounding the figure:


Detailed explanation

Practice Perimeter

Test your knowledge with 83 quizzes

Find the perimeter of the triangle ABC

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Examples with solutions for Perimeter

Step-by-step solutions included
Exercise #1

AB = 10.5

CD = 13

AC = 7.5

BD = 7.5

Calculate the perimeter of the rectangle ABCD.

10.510.510.57.57.57.51313137.57.57.5AAABBBDDDCCC

Step-by-Step Solution

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

  • Step 1: Gather the given side lengths of quadrilateral ABCD.

  • Step 2: Since it's necessary to understand summation, add all lengths.

  • Step 3: Conclude from sum.

Now, let's work through each step:

Step 1: The problem provides:
AB=10.5,CD=13,AC=7.5,BD=7.5. \begin{aligned} AB &= 10.5, \\ CD &= 13, \\ AC &= 7.5, \\ BD &= 7.5. \end{aligned}

Step 2: Add them together:
Perimeter=AB+CD+AC+BD=10.5+13+7.5+7.5. \begin{aligned} \text{Perimeter} &= AB + CD + AC + BD \\ &= 10.5 + 13 + 7.5 + 7.5. \end{aligned}

Step 3: Calculate: Perimeter=10.5+13+7.5+7.5=38.5. \begin{aligned} \text{Perimeter} &= 10.5 + 13 + 7.5 + 7.5 = 38.5. \end{aligned}

Therefore, the solution is that the perimeter of quadrilateral ABCD is 38.5 38.5 .

Answer:

38.5

Video Solution
Exercise #2

AB = 5

CD = 7

AC = 4

BD = 4

Calculate the perimeter of the rectangle.

555444777444AAABBBDDDCCC

Step-by-Step Solution

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

  • Step 1: Identify the given measurements for the sides.

  • Step 2: Use the perimeter formula for a trapezoid, which is summing all sides.

  • Step 3: Add the values to get the perimeter.

Now, let's work through each step:

Step 1: The problem gives us four sides to consider. These sides are: AB=5 AB = 5 , CD=7 CD = 7 , AC=4 AC = 4 , and BD=4 BD = 4 .

Step 2: The perimeter of a trapezoid or any quadrilateral is simply the sum of all four sides. Hence, we need to add AB AB , CD CD , AC AC , and BD BD .

Step 3: Adding the values, we calculate the perimeter:AB+CD+AC+BD=5+7+4+4=20 AB + CD + AC + BD = 5 + 7 + 4 + 4 = 20 .

Therefore, the perimeter of the given shape is 20 20 .

Answer:

20

Video Solution
Exercise #3

A circle has a radius of 3 cm.

What is its perimeter?

333

Step-by-Step Solution

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

  • Step 1: Identify the formula for the circumference of a circle as C=2πr C = 2\pi r .
  • Step 2: Substitute the known value of the radius into the formula.
  • Step 3: Simplify to find the circumference.

Now, let's work through each step:
Step 1: The formula for the circumference, C C , is C=2πr C = 2\pi r .
Step 2: Substitute the given radius r=3 r = 3 cm into the formula:
C=2π×3 C = 2\pi \times 3 .
Step 3: Perform the multiplication:
C=6π C = 6\pi .
Thus, the circumference of the circle is 6π 6\pi cm.

Therefore, the solution to the problem is 6π 6\pi cm.

Answer:

6π 6\pi cm

Video Solution
Exercise #4

Calculate the perimeter of the following parallelogram:

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Step-by-Step Solution

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

  • Step 1: Identify the given information
  • Step 2: Apply the appropriate perimeter formula for the parallelogram
  • Step 3: Perform the necessary calculations

Now, let's work through each step:
Step 1: The problem gives us the lengths of two adjacent sides of the parallelogram: a=10a = 10 and b=8b = 8.
Step 2: We'll use the formula for the perimeter of a parallelogram: P=2(a+b)P = 2(a + b).
Step 3: Plugging in our values, we get:

P=2(10+8)=2×18=36 P = 2(10 + 8) = 2 \times 18 = 36

Therefore, the perimeter of the parallelogram is 3636.

Answer:

36

Video Solution
Exercise #5

Calculate the perimeter of the following parallelogram:

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Step-by-Step Solution

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

  • Step 1: Identify the base and side of the parallelogram from the diagram.
  • Step 2: Use the perimeter formula for a parallelogram.
  • Step 3: Substitute the values into the formula to find the perimeter.

Now, let's work through each step:
Step 1: From the diagram, the base of the parallelogram is given as 3 3 units (top side). Despite the lack of explicit vertical length values, the common approach is to assume symmetrical side lengths—both the base and the side given symmetrically leads us to a second side, typically directly inferred. However, since all clear interpretation points to utilizing 1 and horizontal 3, we verify with associated edge matching.
Step 2: Use the formula for the perimeter of the parallelogram: P=2×(base+side) P = 2 \times (\text{base} + \text{side}) .
Step 3: Substitute the given values into the formula: P=2×(3+1) P = 2 \times (3 + 1) .
Calculating this gives us: P=2×4=8 P = 2 \times 4 = 8 .

Therefore, the solution to the problem is P=8 P = 8 .

Answer:

8

Video Solution

Frequently Asked Questions

What is the formula for finding the perimeter of a triangle?

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The perimeter of a triangle is found by adding all three sides together: P = a + b + c, where a, b, and c are the lengths of the three sides. This formula works for all types of triangles including scalene, isosceles, and equilateral triangles.

How do you find the perimeter of an equilateral triangle?

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For an equilateral triangle, all three sides are equal in length. The formula is P = 3a, where 'a' is the length of one side. Simply multiply the side length by 3 to get the perimeter.

What information do I need to find an isosceles triangle's perimeter?

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For an isosceles triangle, you need the length of the base and the length of one of the two equal sides. The formula is P = base + 2(equal side), since two sides have the same measurement.

Can triangle perimeter be measured in different units?

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Yes, triangle perimeter can be measured in various units including: • Millimeters (mm) • Centimeters (cm) • Meters (m) • Inches or feet Remember to convert units when necessary: 1 cm = 10 mm, 1 meter = 100 cm.

How do I solve triangle perimeter word problems?

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Follow these steps: 1) Identify what type of triangle you have, 2) Write down the known side lengths, 3) Apply the appropriate perimeter formula, 4) Add the measurements carefully, 5) Include the correct units in your final answer.

What's the difference between perimeter and area of a triangle?

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Perimeter measures the distance around the outside of a triangle by adding all three sides together. Area measures the space inside the triangle using the formula A = ½ × base × height. Perimeter is measured in linear units (cm, m) while area uses square units (cm², m²).

Can I find a missing side if I know the triangle's perimeter?

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Yes, if you know the perimeter and two side lengths, you can find the third side using: missing side = perimeter - (side 1 + side 2). This works because the perimeter equals the sum of all three sides.

What are common mistakes when calculating triangle perimeter?

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Common errors include: forgetting to add all three sides, mixing up different units of measurement, confusing perimeter with area formulas, and making arithmetic mistakes when adding the side lengths. Always double-check your addition and units.

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