Let be a triangle such that and let be the feet of the altitudes from and , respectively. Let the circumcircle of triangle be . We draw three lines, tangent to the circumcircle of triangle at , and . Compute the area of the triangle these three lines determine.
Solution
Note that . Let the vertices of the triangle whose area we wish to compute be , opposite respectively. Since are isogonal conjugates, line passes through the circumcenter of , so . Let be the midpoint of . We claim that . This can be seen by angle chasing at to find that , and noting that is the circumcenter of . So, the height from to is the height from to , and thus if is the area of , the area we want is . Heron's formula gives , and similar triangles and give , , so that , since the height from to is 12 . So our answer is .
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