An obtuse triangle is a triangle with one angle measuring more than 90 degrees, also called an obtuse angle, and two acute angles (measuring less than 90 degrees). The sum of the three angles in an obtuse triangle is always greater than 180 degrees. In other words, one angle in the triangle is "obtuse" or wider than a right angle, while the other two angles are acute, or narrower than a right angle.

To find the perimeter of an obtuse triangle, you need to add up the lengths of all three sides of the triangle.

An example of when you might need to find the perimeter of an obtuse triangle is when you are building a roof for a house. The roof may have an obtuse angle where two sides of the roof meet, and you need to find the total length of the material needed to cover all three sides of the triangle-shaped roof.

The formula for determining the perimeter of an obtuse triangle is defined as: