To form a triangle, 3 line segments are needed. We can choose 3 line segment from 5 line segments in $^5C_3$ ways. We know that in a triangle, sum of two sides is always greater than third side. So, line segments of length (2, 3, 5), (2, 3, 6) and (2, 4, 6) do not form any triangle. $\therefore$ Total number of triangles formed = $^5C_3 - 3$