MathDB
Regular Dodecagon

Source:

March 3, 2010
geometrytrigonometry

Problem Statement

A regular dodecagon (12 12 sides) is inscribed in a circle with radius r r inches. The area of the dodecagon, in square inches, is: <spanclass=′latex−bold′>(A)</span> 3r2<spanclass=′latex−bold′>(B)</span> 2r2<spanclass=′latex−bold′>(C)</span> 3r234<spanclass=′latex−bold′>(D)</span> r23<spanclass=′latex−bold′>(E)</span> 3r23 <span class='latex-bold'>(A)</span>\ 3r^2 \qquad <span class='latex-bold'>(B)</span>\ 2r^2 \qquad <span class='latex-bold'>(C)</span>\ \frac{3r^2 \sqrt{3}}{4} \qquad <span class='latex-bold'>(D)</span>\ r^2 \sqrt{3} \qquad <span class='latex-bold'>(E)</span>\ 3r^2 \sqrt{3}
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