In order to prove that there are only four of these triangles, we need to first restate the formula for the perimeter of a triangle which is given as: P = a + b + c. Hence, we must identify all the triangles that have two or more equal sides, and each side is a whole number.
Step 1 - First, we state all the possible combination three whole numbers which when added together result in fifteen.
The numbers are given as:
Step 2 - Eliminate options where a side is more than the sum of the other two sides
Hence,
are eliminated. The remaining triangles are four in number.
QED.
Learn more about triangles at:
https://brainly.com/question/17335144
#SPJ1