The sum of the interior angles, s, in an n-sided polygon can be determined using the formula s=180(n−2), where n is the number of sides.Using this formula, how many sides does a polygon have if the sum of the interior angles is 1,260°? Round to the nearest whole number.
Answer
A
6 sides
B
7 sides
C
8 sides
D
9 sides
Explanation
Substitute 1,260° for s in the formula: 1,260 = 180(n − 2). Divide both sides by 180 to get 7 = n − 2, so n = 9. The polygon has 9 sides, which is choice D.
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