SOLUTION: Hi, 1. suppose that the sum of the measures of the vertex angles of a polygon is 1620 degrees. How many sides does the polygon have? what I've tried: (n-2)180/n= i multipli

Algebra ->  Polygons -> SOLUTION: Hi, 1. suppose that the sum of the measures of the vertex angles of a polygon is 1620 degrees. How many sides does the polygon have? what I've tried: (n-2)180/n= i multipli      Log On


   



Question 569498: Hi,
1. suppose that the sum of the measures of the vertex angles of a polygon is 1620 degrees. How many sides does the polygon have?
what I've tried:
(n-2)180/n= i multiplied "n" by both sides to cancel out the fraction and then use distribution property to fix the equation.
180n - 360= 1620n
-180n 180n
-360= 1440n
-0.25=n
but that is the wrong answer. the book says that the answer of sides is 11.
Please help me.

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
I know your frustration. It's hard to figure out one's own mistake, and it is obvious that a polygon could not have -0.25 sides.
%28n-2%29180%2Fn would be the measure of one angle in a regular n-sided polygon. That's probably what you were thinking of, but the problem refers to the sum of the measures of the angles.
The sum of the measures of the vertex angles of an n-sided polygon is %28n-2%29180.
If %28n-2%29180=1620 --> n-2=1620%2F180 --> n-2=9 --> n=9%2B2 --> highlight%28n=11%29