Pensieve header: A computation for Paul Selick. “tp” was generated by C:\drorbn\PrivatePensieve\People\Selick\flc.m.

tp=((6+12 I) (324-324 a+81 (a^2)+16 (ttt^2)) ((36-198 I) (a^2)+a ((-126+693 I)+(296+148 I) x-(148-296 I) y)-6 ((-18+99 I)+(98+49 I) x-(49-98 I) y)) (24 x-7 y) (2 (Sqrt[(x^2)+(y^2)])+(Sqrt[5]) (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)])))/(-8 ttt (24 x-7 y) (-120 (a^2)+5 a (345+14 x+48 y)-6 (495+28 x+96 y))+45 (-2+a) (60 (Sqrt[5]) (a^2) (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)])+a (1125 (Sqrt[(x^2)+(y^2)])+28 x (Sqrt[(x^2)+(y^2)])+96 y (Sqrt[(x^2)+(y^2)])-300 (Sqrt[5]) (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)])-21 (Sqrt[5]) x (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)])-72 (Sqrt[5]) y (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)]))-6 (375 (Sqrt[(x^2)+(y^2)])+14 x (Sqrt[(x^2)+(y^2)])+48 y (Sqrt[(x^2)+(y^2)])-60 (Sqrt[5]) (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)])-7 (Sqrt[5]) x (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)])-24 (Sqrt[5]) y (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)]))));

tp1=tp /. {(Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)])->r1, (Sqrt[(x^2)+(y^2)])->r2}

FullSimplify[ComplexExpand[Re[tp1]] /. {r1 -> (Sqrt[405+180 (a^2)+252 x+500 (x^2)+864 y+500 (y^2)-12 a (45+14 x+48 y)]), r2->(Sqrt[(x^2)+(y^2)])}]