There is an 8-polygons. what is the number of the diagonals of the 8-polygons ?
A. 20 B. 27 C. 32 D. 43 E. 45
is there any formula for this ?
A. 20 B. 27 C. 32 D. 43 E. 45
is there any formula for this ?
when it asks "how many different" they are normally asking for permutations combinations and here that is the case however there is a difference.
First you would solve for the number of combinations of two points out of 8 possible points.
8!/(8-2)!(2!) = 28
However, this accounted for the sides, as a connection between two points that are right next to each other on the shape will form a side, not a diagonal. Therefore you have to subtract the 8 sides from this calculation to get 20
The correct answer is A.
Best of Luck
