Answer : n-sided polygon has n numbers of vertices. Diagonals are formed by joining the opposite vertices from one vertex, except the two adjacent vertices. So, from one vertex (n-3) diagonals can be drawn. Similarly, for n numbers of vertices, n(n-3) diagonals can be drawn. But, the diagonal joins 2 points at a time, here two

vertices. Therefore, the actual number of diagonals is