Question

write the formula to find the number of diagonals of a polygon find the number of diagonals of the following Polygon: 1. pentagon ​

Answer 1

I Have IT'S help ful

Step-by-step explanation:

n(n − 3) / 2

Example

a square (or any quadrilateral) has 4(4−3)/2 = 4×1/2 = 2 diagonals

an octagon has 8(8−3)/2 = 8×5/2 = 20 diagonals.

a triangle has 3(3−3)/2 = 3×0/2 = 0 diagonals.