(Q). If number of triangles that can be drawn from the given set of points as vertices is 56 then find the number of straight lines that can be drawn from these points.
Solution:-
Here it is given that ⁿC₃ = 56
⟹
⟹ n(n-1)(n-2) = 8×7×6
∴ n = 8
Hence number of straight lines = ⁸C₂ = 28 Answer
