SOLUTION: Each exterior angle is 100º less than its interior angle of a regular polygon. Find the number of sides of the polygon. Thank you!

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Question 785529: Each exterior angle is 100º less than its interior angle of a regular polygon. Find the number of sides of the polygon.
Thank you!

Found 2 solutions by KMST, MathTherapy:
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
The exterior and interior angles of a polygon are supplementary *adding to 180^o}}}.
If x = measure of an interior angle in degrees.
180-x = measure of the corresponding exterior angle in degrees.
The problem says that
180-x=x-100, so
180%2B100-x=x
280-x=x
280=x%2Bx
280=2x
280%2F2=x
x=140
and the exterior angles measure 180%5Eo-140%5Eo=40%5Eo
The exterior angles are the angles you have to turn (deviate from your original direction when going around the polygon, so they add to 360%5Eo, because going one full turn around you are doing a 360%5Eo.
This is a regular polygon, so it is very symmetrical:
all the exterior angles measure the same 40%5Eo,
all the interior angles measure the same 140%5Eo, and
all the sides have the same length, which we do not know and do not care.
So if n= number of sides/exterior angles of the regular polygon, and all those exterior angles measure 40%5Eo
n%2A%2840%5Eo%29=360%5Eo so
n=360%5Eo%2F%2840%5Eo%29--> highlight%28n=9%29

Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!

Each exterior angle is 100º less than its interior angle of a regular polygon. Find the number of sides of the polygon.
Thank you!

Let measure of each exterior angle be E
Then measure of each interior angle = E + 100

Since both angles are supplementary, then: E + E + 100 = 180

2E = 180 - 100

2E = 80

E, or measure of each exterior angle = 80%2F2, or 40%5Eo

Since the sum of the measures of the exterior angles of ALL polygons is 360%5Eo, and with each exterior angle of this REGULAR polygon being 40%5Eo, then the number of sides of this polygon = 360%2F40, or highlight_green%289%29