Question

Find the number of diagonals in a:
1. Pentagon
2. Hexagon
3. Octagon

Answer 1

Hey dear
No of diagonal in a polygon =n(n-3)2
n Is the no of side of polygon
So

1) no. Of side in pentagon =5
No. Of diagonal =5(3-2)=5

2) no. Of side in hexagon = 6
No. Of diagonal =6(6-3)2=9

3) no. Of side in octagon =8
No. Of diagonal =8(8-3)2=20

Hope it helps you!!!!!!!