Q.

A polygon has 44 diagonals. The number of its sides are

1 9  
2 8  
3 11  
4 7  

Ans.

(3)

Number of sides=n

Number of vertices=n

Number of diagonals=C2n-n

⇒  44=C2n-n⇒n(n-1)2-n=44

⇒  n2-3n-88=0

∴  n=11                        (∵ n cannot be negative)