# If the sum of all interior angles of a regular polygon is 14 right angles, then its number of sides is :

**Answer is 9 **

**Explanation:-**

The sum of all interior angles of a regular polygon = 14 right angle

= 14 x 90

= 1260º

**Formula-
**

**The sum of all interior angles of a regular polygon = (n – 2) 180º**

**Given-
The sum of all interior angles of a regular polygon = 1260º **

Then, (n – 2) 180º = 1260º

n – 2 = 1260º/180º

n – 2 = 7

n = 7 + 2

n = 9

Then, the side of the polygon is 9.

Hence, the correct answer is option (1) 9.