Respuesta :

We need to use the formula:

(n-2) x 180 =  sum of interior angles

where n is the number of sides.

So,

(n-2) x 180 = 1620
n - 2 = 1620 ÷ 180
n - 2 = 9
n = 9 + 2
n = 11

It has 11 sides!