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Last updated on September 26, 2025
The perimeter of a shape is the total length of its boundary. For a right triangle, the sum of all three sides is called the perimeter. Perimeter calculations are useful in various practical applications such as construction, art, and design. In this topic, we will learn about the perimeter of a right triangle.
The perimeter of a right triangle is the total length of its three sides, including the two legs and the hypotenuse. By adding the lengths of all three sides, we get the perimeter of the shape.
The formula for the perimeter of a right triangle is π = π + π + π, where a and b are the legs and c is the hypotenuse. For instance, if a right triangle has legs a = 3, b = 4, and hypotenuse c = 5, then its perimeter is P = 3 + 4 + 5 = 12.
Let’s consider another example of a right triangle with side lengths π = 5, π = 12, and π = 13.
So the perimeter of the right triangle will be: π = π + π + π = 5 + 12 + 13 = 30.
To find the perimeter of a right triangle, apply the formula by summing all the sides of the triangle.
For instance, for a right triangle with sides a = 6, b = 8, and c = 10, the perimeter = sum of all sides = 6 + 8 + 10 = 24 cm.
Example Problem on Perimeter of Right Trangle
To find the perimeter of a right triangle, use the formula, π = π + π + π.
For example, let’s say, a = 9 cm, b = 12 cm, and c = 15 cm.
Now, the perimeter = sum of all sides = 9 + 12 + 15 = 36 cm.
Therefore, the perimeter of the right triangle is 36 cm.
Learning some tips and tricks makes it easier to calculate the perimeter of right triangles.
Here are some tips and tricks:
While working with the perimeter of a right triangle, errors can occur. Here are solutions to common problems:
A triangular roof has a perimeter of 60 feet, with two sides measuring 20 feet each. To find the missing side, subtract the sum of the known sides from the total perimeter.
Length of the missing side = 20 feet.
Let ‘c’ be the missing side.
Given perimeter = 60 feet.
Length of the two equal sides = 20 feet.
Perimeter of the triangle = sum of lengths of three sides.
60 = 20 + 20 + c
60 = 40 + c
c = 60 - 40
= 20
Therefore, the missing side is 20 feet.
A wire with a perimeter of 300 inches is bent into a right triangle with two equal legs. Find the length of each leg.
100 inches
Given the perimeter of the wire forms a right triangle with two equal legs:
Perimeter = a + a + c = 300
Assuming a = b, and using a = b = x, the perimeter becomes: 2x + c = 300.
If c is determined to be a specific value or calculated, solve for x accordingly.
For this example, let's assume c is such that: x = 100.
Find the perimeter of a right triangle with legs of 9 cm and 12 cm.
36 cm
First, find the hypotenuse using the Pythagorean theorem:
c = √(9² + 12²)
= √(81 + 144)
= √225
= 15.
Now, calculate the perimeter:
Perimeter of triangle = a + b + c
P = 9 + 12 + 15 = 36 cm.
Therefore, the perimeter of the right triangle is 36 cm.
James is designing a triangular flag with sides: Side A = 8 meters Side B = 15 meters Hypotenuse (Side C) = 17 meters How much trim does James need to go around the edge of the flag?
James will need 40 meters of trim to go around the flag.
The perimeter of a triangle is the sum of all three sides.
Using the formula: P = a + b + c
P = 8 + 15 + 17
= 40 meters.
Find the perimeter of a right triangular ramp with base = 7 meters, height = 24 meters.
Perimeter = base + height + hypotenuse Hypotenuse = √(7² + 24²)
= √(49 + 576)
= √625
= 25 meters.
Perimeter = 7 + 24 + 25 = 56 meters.
The hypotenuse of the right triangle is calculated using the Pythagorean theorem.
The entire distance around the ramp is calculated to be 56 meters by summing the lengths of the three sides.
Seyed Ali Fathima S a math expert with nearly 5 years of experience as a math teacher. From an engineer to a math teacher, shows her passion for math and teaching. She is a calculator queen, who loves tables and she turns tables to puzzles and songs.
: She has songs for each table which helps her to remember the tables