Question

Find the number of diagonals of a polygon of 13 sides.

Answer 1

Answer:

65

Step-by-step explanation:

13(13-3)/2 = 65 diagonals.

Answer 2

n(n-3)/2 is the number of diagonals. Explain in words why this works. A 13-gon would have 13(13-3)/2 = 65 diagonals.