Answer:
NO, it can have only 189 possible diagonals
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.