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imc

geometry intermediate

Problem

Let be an equiangular hexagon. The lines and determine a triangle with area , and the lines and determine a triangle with area . The perimeter of hexagon can be expressed as , where and are positive integers and is not divisible by the square of any prime. What is ?
(A)
(B)
(C)
(D)
Solution
Let and be the intersections and respectively. The sum of the interior angles of any hexagon is Since hexagon is equiangular, each of its interior angles is By angle chasing, we conclude that the interior angles of and are all Therefore, these triangles are all equilateral triangles, from which and are both equilateral triangles. We are given that \begin{alignat}{8} [PQR]&=\frac{\sqrt{3}}{4}\cdot PQ^2&&=192\sqrt3, \\ [XYZ]&=\frac{\sqrt{3}}{4}\cdot YZ^2&&=324\sqrt3, \end{alignat} so we get and respectively. By equilateral triangles and segment addition, we find the perimeter of hexagon Finally, the answer is
Final answer
C