What is the perimeter of triangle ABC

Well since we don't know the measurements of said triangle, I can only give you the formula for perimeter of a triangle.

Add each side length together to get the perimeter. For example, say we have a triangle with the side lengths 8, 9, and 3. To find the perimeter of this triangle, add each side length together.

8 + 9 + 3 = 20

The perimeter would be 20, or the sum of the given sides.