How many non-congruent triangles have vertices at three of the eight points in the figure?
I think the best way to solve this is to just start counting.
Sides:
1, 1, sqrt(2)
1, 2, sqrt(5)
1, 3, sqrt(10)
sqrt(2), sqrt(2), 2
sqrt(2), sqrt(5), 4
That's 5. :))
=^._.^=
