Advent calendar 2023
1 December
Each interior angle of a regular triangle is 60°.
Each interior angle of a different regular polygon is 178°. How many sides does this polygon have?
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The exterior angles of any polygon add up to 360°.
The interior angles of our polygon are 178°, and so the exterior angles are 2°. There must be 180 sides (and so also 180 angles) on the polygon, as 180×2=360.