How many non congruent triangles with positive integer side lengths have perimeter less than 15?
Please note: the sum of any two sides is greater than the third!
Using casework on the smallest side, and list triangles:
(2,6,7)
(3,5,7)
(4,4,7)
(5,5,5)
===> four triangles
please read the question. It says less than 15
+421 
