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Geometry Level 4

Consider an acute triangle A B C ABC with X X as the foot of the perpendicular from A A to B C BC . Let the circle Ω \Omega with A X AX as the diameter intersect A B AB and A C AC at D D and E E respectively. Let B E BE and C D CD intersect circle Ω \Omega at E E' and D D' respectively. If the measures of the angles E A X , E E D , D A X E'AX, EE'D', D'AX and E B C EBC are a , b , c a,b,c and d d respectively, and sin ( a ) sin ( b ) sin ( c ) sin ( d ) = x y \dfrac{\sin (a) \sin(b)}{\sin(c) \sin(d)} = \dfrac xy for coprime positive integers x x and y y , calculate x + y x+y .


The answer is 2.

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1 solution

For those who want/need a solution

also, it would be advised if you actually tried it out instead of guessing the values for x and y :)

Yooowazzup Yooowazzup - 5 years, 10 months ago

Once we prove the cyclicity of BDEC, we can immediately prove the parallelism: use the fact that DED'E' is a cyclic quadrilateral as well

Yooowazzup Yooowazzup - 5 years, 10 months ago

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