Finding the perimeter of a polygon.
Geometry
Level
pending
All triangles shown in the above figure are equilateral. The radius of the green circle is 10 units. What is the perimeter of the blue polygon?
The answer is 120.
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1 solution
Since all triangles are equilateral, the red polygon must be a regular hexagon. Hence, the side length is also 1 0 . So the perimeter of the blue polygon is 1 2 ( 1 0 ) = 1 2 0 .