# Perimeter of a Right Triangle

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The perimeter of a right triangle is the sum of the lengths of the two legs and the hypotenuse (in other words, the sum of all three sides).

Download this calculator to get the results of the formulas on this page. Choose the initial data and enter it in the upper left box. For results, press ENTER.

Note. Courtesy of the author: José María Pareja Marcano. Chemist. Seville, Spain.

## Exercise: How to Find the Perimeter of a Right Triangle

We can find the perimeter of a right triangle whose sides are a=3 cm, b=4 cm and c=5 cm by adding all the three sides:

The perimeter of the triangle is 12 cm.

## How to Find the Perimeter of a Right Triangle using the Leg Rule

The Leg Rule relates the length of each leg of a right triangle with the segments projected by them on the hypotenuse.

According to the equation derived from the Leg Rule we can calculate the lengths of the two legs in a right triangle if the hypotenuse and the two projections (m and n) of the legs (a and b) on the hypotenuse are given.

So, we get the following formulas for each leg:

If perimeter is equal to a + b + c.

Where m and n are the segments projected by the legs (a and b) and c is the hypotenuse.

The Leg Rule is useful when the two legs (a and b) are unknown.

AUTHOR: Bernat Requena Serra

YEAR: 2020