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Sometimes, problem proposers at competitions are not too creative, and instead of coming up with new ideas, they give a well-known problem a makeover to scare people off. Or when researching a complicated theory, a simple step turns out to be an easy consequence of one of the building blocks of this theory.

At a competition, one can tell that a problem is a redecorated problem if it appears very complicated, hideous, or scary. You might feel that something should be easy, possibly a déjà vu feeling, an idea you still can't quite put your finger around.

In conclusion, a complicated problem environment should tell you to try removing irritating elements so you could see the big picture.

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The circles C1C_1 and C2C_2 with diameters ABAB and ACAC, and centers O1O_1 and O2O_2 respectively, intersect each other at AA and PP.

The perpendicular to O2PO_2P through BB meets the perpendicular to O1PO_1P through CC at QQ. The parallel to ABAB through O2O_2 meets the parallel to ACAC through O1O_1 at MM.

Let the parallel to BCBC through QQ meet the circumcircle of △ABC\triangle ABC at QQ and R≠QR\neq Q. Finally, let UU be the intersection of lines RMRM and APAP.

Prove that if SS is on ABAB and TT on ACAC such that QS,CUQS,CU are parallel and QT,BUQT,BU are parallel, then SS, PP, and TT lie on a line.

(Source)

Type a concept, like “slope” or “photosynthesis”.

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