Question

the number of diagonals of a polygon is 2.5 times its sides.Find the number of sides of the polygon

Answer 1

There is a simple formula for calculating the number of diagonals of a polygon.

No. of diagonals = n(n - 3) ÷ 2

where n is the number of sides.

Here, n(n -3) = 5n

n^2 - 3n = 5n

n^ 2 = 8n

n = 8

So the polygon is octagon.