SOLUTION: Work out the size of an exterior and an interior angle of a regular 18-sided polygon.

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Question 1158275: Work out the size of an exterior and an interior angle of a regular 18-sided polygon.

Found 2 solutions by math_helper, Alan3354:
Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!
Total sum of interior angles = 180*(number of sides - 2) (think about how many triangles you can draw, each has 180 degrees).

180(18-2) = 2880

2880/18 = 160%5Eo for each interior angle of a regular 18-gon

Each exterior angle is the supplement to the interior angle: 180-160 = +20%5Eo+
[ Also note: there are 360 degrees around the 18-gon, so another way to find the exterior angle is to divide 360 by the number of sides: 360/18 = 20 ]

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Work out the size of an exterior and an interior angle of a regular 18-sided polygon.
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Find the Ext angles first:
360/18 = 20 degs
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Int = 180 - 20 = 160 degs