# Geometry

The sum of the interior angles of polygon is 1800. Find the number of sides in the polygon and, what do you call that polygon?

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1. for n sides
exterior angle = 360/n
so interior angle = 180 - 360/n
sum of interior angles = n(180 - 360/n)
=180 n (1 - 2/n)
so here
1800 = 180 n (1 - 2/n)
10 = n - 2
n = 12 sides

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2. duodecagon I mean

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3. glooks

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