Problem 91
Right triangles with integer coordinates
The points P (x1, y1) and Q (x2, y2) are plotted at integer co-ordinates and are joined to the origin, O(0,0), to form ΔOPQ.
There are exactly fourteen triangles containing a right angle that
can be formed when each co-ordinate lies between 0 and 2 inclusive; that
is,
0 
x1, y1, x2, y2 2.
Given that 0 x1, y1, x2, y2 50, how many right triangles can be formed?
These problems are part of Project Euler and are licensed under CC BY-NC-SA 2.0 UK