Problem 5

A 5-by-5 pegboard has a single peg in, glued into one of the corners. How many ways can we put two more pegs in the board so that the 3 pegs form a right angled triangle?

Three 5-by-5 grids illustrating the pegboard, the first is empty, the second has three pegs in which form a right triangle, the third has three pegs in which don