How many distinct triangles could be drawn using as their vertices three of the vertices of a regular hexagon?
(A) 6
(B) 12
(C) 15
(D) 20
(E) 30
(A) 6
(B) 12
(C) 15
(D) 20
(E) 30
IMO DNight reader wrote:How many distinct triangles could be drawn using as their vertices three of the vertices of a regular hexagon?
(A) 6
(B) 12
(C) 15
(D) 20
(E) 30
In a hexagon none of the 3 points are co-linear so we do not have to subtract anything.
Thus, C(6,3) = 20.
