Question

There is a polygon has 6 sides and another polygon has 7 sides, then find out the difference between the number of diagonals between them. 
1. 3
2. 4
3. 5
4. 6

Answer 1

Correct Answer - Option 3 : 5

Given :

There are 2 polygons having sides 6 and 7 respectively 

Formula used :

No of diagonals = n(n-3)/2 (where n is the number of sides)

Calculations :

When n = 6, Number of diagonals = 6× (6-3)/2 = 9 

When n = 7, Number of diagonals = 7 × (7-3)/2 = 14 

Difference between the number of diagonals = 14 - 9 

⇒ 5 

∴ Difference between number of diagonals is 5