In a regular polygon, each interior angle measures exactly eight times as large as one of its exterior angles. How many sides does this polygon have?
18 sides
An interior angle i and an exterior angle e sum to 180 degrees. Since i = 8e, we have 9e = 180 degrees, which means e = 20 degrees. The number of sides in any regular polygon is 360 / e, so 360 / 20 = 18 sides.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Medium. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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