Question

How many diagonals are there in a polygon having 12 sides ? (a) 12 (b) 24 (c) 36 (d) 54

Answer 1

In a polygon of 12 sides, no. of diagonals $\frac{n(n-3)}{2}=\frac{12(12-3)}{2}=\frac{12\times 9}{2}=54$