The total distance around the outside of a
Drag any orange dot to resize the triangle. The perimeter is calculated as you drag.
How to find the perimeter of a triangle
Like any polygon, the perimeter is the total distance around the outside,
which can be found by adding together the length of each side.
Or as a formula:
a,b and c are the lengths of each side of the triangle
In the figure above, drag any orange dot to resize the triangle. From the side lengths shown, calculate the perimeter
and verify your result matches the formula at the top of the diagram.
Other triangle topics
Perimeter / Area
Congruence and Similarity
Triangle quizzes and exercises
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