Help! I'm unsure as to how to solve this... True or false? Can a polygon with 21 sides have 432 possible diagonals.

NO, it can have only 189 possible diagonals

Step-by-step explanation:

No. of diagonals in a polygon is given by n(n-3)/2

where n is the number of sides in the polygon.

Given

polygon has 21 sides

thus, no. of diagonals for 21 sided polygon is = 21(21-3)/2 = 21*18/2 = 189

while in the problem it is asking if it has 432 possible diagonals

which is wrong.