*All the sides of a triangle have integer length. The perimeter of the triangle is 50 and the triangle is isosceles. How many such non-congruent triangles are there?*

Let s be the length of two of the sides and b be the length of the third side.

We must have \(50=2s+b\) and \(b<2s\)

Try values of s from 1 upwards until the second expression above is violated, remembering that b must be an integer.