## Polygons

If the sum of the interior angle of a regular polygon is 1,260 degrees, how many sides does the polygon have?

A. 6

B. 8

C. 9

D. 12

E. 14

## Knowsys Method

**Read the question carefully. **You know that in a regular polygon, all the sides have the same length and all of the angles have the same measure.

**Identify the bottom line. **# of sides = ?

**Assess your options. **You should use the polygon rule to find the answer. The polygon rule is:

total degrees = 180(n - 2)

The variable "n" represents the number of vertices, which is equal to the number of sides for a regular polygon.

**Attack the problem.**

total degrees = 180(n - 2)

1,260 = 180(n - 2)

7 = n - 2

9 = n

**Loop back. **The number that you found represents both the number of angles and the number of sides, so you are done!

The correct answer is (C).

This is a medium level question.

**Want some help reviewing the math concepts you need to master? **Try out the Knowsys Pre-Algebra Flashcards, the Knowsys Algebra I Flashcards, and the Knowsys SAT & ACT Math Practice book.