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Problem 377: (2009 AMC 12A, 19)
Andrea inscribed a circle inside a regular pentagon, circumscribed a circle around the pentagon, and calculated the area of the region between the two circles. Bethany did the same with a regular heptagon (7 sides). The areas of the two regions were $A$ and $B$, respectively. Each polygon had a side length of $2$. Which of the following is true? $\textbf{(A)}\ A = \frac {25}{49}B\qquad$ $ \textbf{(B)}\ A = \frac {5}{7}B\qquad$ $ \textbf{(C)}\ A = B\qquad$ $ \textbf{(D)}\ A$ $= \frac {7}{5}B\qquad$ $ \textbf{(E)}\ A = \frac {49}{25}B$
Solution
Exercise 377: Solution
Andrea inscribes a circle inside a regular hexagon, circumscribes a circle around it, and calculates the area between them (region $A$). Bethany does the same with a regular nonagon (9 sides). Both polygons have side length $3$. Which of the following is true of the areas $A,B$?
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