The animation on the right shows the circle inscribing the triangle whose one of the sides is the diameter with two fixed endpoints. The point is selected and rotated counterclockwise on the circumference, so that the Nagel point of the triangle forms the locus colored in purple.
If the following area ratio is
Input as your answer.
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If the points A , B , C have coordinates ( − 1 , 0 ) , ( 1 , 0 ) and ( cos 2 θ , sin 2 θ ) respectively (we are writing ∠ B A C = θ ), then the Nagel points N a is the intersection of the lines A D and B E , where 2 + A E = 2 + B D is equal to the semiperimeter 1 + cos θ + sin θ of the triangle A B C . This means that D E ( 1 − ( sin θ + cos θ − 1 ) sin θ , ( sin θ + cos θ − 1 ) cos θ ) ( − 1 + ( sin θ + cos θ − 1 ) cos θ , ( sin θ + cos θ − 1 ) sin θ ) and hence the Nagel point has coordinates N a ( x ( θ ) , y ( θ ) ) = ( cos 2 θ + 2 sin θ − 2 cos θ , ( sin θ + cos θ − 1 ) 2 ) and so the upper half of the area enclosed by the locus of the Nagel point is A = ∫ 0 2 1 π x ′ ( θ ) y ( θ ) d θ = 8 − 2 5 π Thus the desired proportion is R = π 2 A = π 1 6 − 5 = 0 . 0 9 2 9 5 8 1 7 8 9 4 . . . and hence ⌊ 1 0 6 R ⌋ = 9 2 9 5 8 .