X110

FOCUS OF KIEPERT PARABOLA

Scimemi proves that if the Euler line is reflected in every side of triangle ABC, then the three reflections concur in X110.
< A B C >: Reference Triangle △ABC [ A B ]: Sideline AB (Base c = 1) [ B C ]: Sideline BC (Side a) [ C A ]: Sideline CA (Side b) circumcircle: Circumcircle of △ABC { 5, 49 }: Central Line L(5, 49) { 1, 60 }: Central Line L(1, 60) { 3, 74 }: Central Line L(3, 74) { 2, 98 }: Central Line L(2, 98) A = Vertex A (0.0000, 0.0000) B = Vertex B (1.0000, 0.0000) C = Vertex C (0.6122, 0.5999) X_3 = CIRCUMCENTER (0.5000, 0.1021) X_5 = NINE-POINT CENTER (0.5561, 0.2489) X_49 = CENTER OF SINE-TRIPLE-ANGLE CIRCLE (0.6275, 0.1789) X_1 = INCENTER (0.5714, 0.2333) X_60 = ISOGONAL CONJUGATE OF X(12) (0.5790, 0.2258) X_74 = ISOGONAL CONJUGATE OF EULER INFINITY POINT (0.7484, -0.3437) X_2 = CENTROID (0.5374, 0.2000) X_98 = TARRY POINT (0.8891, -0.2281) X_110 = FOCUS OF KIEPERT PARABOLA (0.2516, 0.5478) A B C X3 X5 X49 X1 X60 X74 X2 X98 X110 (a, b, c) = (5, 6, 7) | AB = 1

X110 (FOCUS OF KIEPERT PARABOLA) constructed on acute reference triangle \((a, b, c) = (5, 6, 7)\) with unit baseline AB = \(1\).

Constructed Elements

  • Circle: Circumcircle (circumcircle) — Passes through vertices A, B, C; centered at X3 CIRCUMCENTER

  • Related Centers: X3 (CIRCUMCENTER)

Trilinears: \(\csc(B - C) : \csc(C - A) : \csc(A -B)\)
Barycentrics: \(a^{2}/(b^{2} - c^{2}) : :\)
Tripolars: \(|\sin(B - C)| : :\)
Search Value (6, 9, 13): \(0.907562974102\)
▸ Alternate Coordinates4 forms
  • Trilinears: \(\cos(B - C) - \cos(C - A) \cos(A - B) : :\)

  • Trilinears: \(a/(b^{2} - c^{2}) : :\)

  • Trilinears: \(\sec(B - C) - \sec(C - A) \sec(A - B) : :\)

  • Tripolars: \(|b c (b^{2} - c^{2})| : :\)

X110 lies on the circumcircle, Walsmith rectangular hyperbola, Parry circle.

▸ Incident Central Lines993 lines

{1, 60}, {2, 98}, {3, 74}, {4, 113}, {5, 49}, {6, 111}, {10, 2372}, {11, 215}, {12, 2477}, {13, 3200}, {14, 3201}, {15, 2378}, {16, 2379}, {17, 3205}, {18, 3206}, {20, 146}, {21, 104}, {22, 154}, {23, 323}, {24, 155}, {25, 1112}, {26, 7731}, {27, 917}, {28, 915}, {29, 2988}, {30, 477}, {31, 593}, {32, 729}, {33, 9637}, {35, 501}, {36, 5127}, {39, 755}, {40, 37405}, {41, 35106}, {42, 28482}, {48, 2249}, {50, 32730}, {51, 1994}, {52, 2383}, {55, 3024}, {56, 3028}, {58, 106}, {59, 2222}, {61, 2380}, {62, 2381}, {63, 6061}, {64, 5896}, {65, 229}, {66, 15116}, {67, 141}, {68, 7505}, {69, 206}, {75, 21430}, {76, 2367}, {81, 105}, {83, 3203}, {86, 675}, {97, 418}, {99, 690}, {100, 643}, {101, 163}, {102, 283}, {103, 1790}, {107, 648}, {108, 162}, {109, 1813}, {112, 1625}, {115, 3044}, {116, 3046}, {126, 3048}, {140, 10264}, {143, 195}, {148, 16278}, {149, 19642}, {159, 12220}, {165, 9904}, {183, 9769}, {185, 17701}, {186, 7722}, {187, 352}, {190, 835}, {193, 1974}, {199, 22139}, {213, 2375}, {235, 22750}, {237, 2080}, {248, 9513}, {249, 512}, {250, 520}, {251, 694}, {255, 26701}, {270, 3562}, {274, 767}, {275, 30506}, {284, 2291}, {290, 36901}, {324, 436}, {325, 2857}, {333, 1311}, {343, 10192}, {351, 526}, {353, 574}, {355, 12889}, {371, 7598}, {372, 7599}, {373, 575}, {376, 541}, {378, 11472}, {381, 7699}, {382, 1539}, {384, 35399}, {385, 9418}, {386, 3031}, {389, 12227}, {395, 11134}, {396, 11137}, {402, 13212}, {403, 32123}, {467, 23233}, {468, 3564}, {476, 523}, {489, 30427}, {490, 30428}, {493, 13215}, {494, 13216}, {513, 1290}, {514, 2690}, {515, 2695}, {516, 2688}, {517, 1325}, {518, 2752}, {519, 2758}, {521, 2766}, {522, 2689}, {524, 2770}, {525, 935}, {539, 37943}, {543, 9144}, {546, 37472}, {548, 14677}, {549, 11694}, {550, 8718}, {560, 715}, {568, 12106}, {569, 3090}, {573, 34453}, {576, 9716}, {577, 26717}, {578, 3091}, {588, 8956}, {595, 849}, {599, 6325}, {620, 15357}, {631, 6699}, {632, 37471}, {645, 3952}, {647, 2715}, {649, 2702}, {650, 9090}, {660, 4599}, {663, 2701}, {664, 1305}, {667, 2703}, {668, 839}, {669, 805}, {670, 689}, {671, 5465}, {677, 23090}, {681, 823}, {685, 850}, {693, 2864}, {699, 1501}, {707, 18899}, {719, 1923}, {727, 2206}, {737, 3117}, {739, 1333}, {745, 1964}, {753, 3736}, {758, 12030}, {789, 799}, {813, 1252}, {825, 28860}, {826, 1287}, {827, 4611}, {833, 3888}, {840, 3286}, {841, 7464}, {846, 19655}, {858, 1503}, {859, 953}, {868, 6033}, {880, 4609}, {892, 8599}, {898, 4567}, {901, 1618}, {902, 1326}, {905, 2722}, {906, 36080}, {912, 2074}, {916, 2073}, {919, 5098}, {924, 10420}, {925, 1632}, {927, 4573}, {929, 4560}, {930, 13290}, {931, 4612}, {933, 13318}, {934, 1414}, {942, 1175}, {946, 37369}, {952, 3109}, {960, 1798}, {972, 1817}, {974, 1181}, {1010, 24809}, {1014, 15728}, {1019, 1308}, {1043, 2370}, {1055, 5060}, {1062, 9638}, {1098, 2975}, {1101, 2605}, {1109, 2606}, {1113, 2574}, {1114, 2575}, {1125, 13605}, {1151, 7601}, {1152, 7602}, {1154, 2070}, {1155, 11670}, {1157, 15907}, {1169, 2300}, {1171, 2054}, {1172, 8759}, {1173, 1493}, {1193, 38453}, {1194, 34945}, {1199, 5462}, {1205, 11574}, {1209, 9379}, {1216, 7512}, {1289, 2409}, {1291, 1510}, {1292, 2775}, {1293, 2776}, {1295, 2778}, {1296, 2434}, {1301, 2445}, {1302, 2407}, {1309, 5379}, {1310, 4592}, {1316, 2782}, {1320, 31523}, {1329, 9701}, {1340, 6142}, {1341, 6141}, {1370, 1660}, {1379, 5638}, {1380, 5639}, {1384, 9486}, {1396, 2376}, {1397, 17127}, {1408, 8686}, {1412, 1477}, {1415, 32693}, {1428, 7292}, {1434, 2369}, {1469, 32289}, {1473, 26910}, {1474, 9085}, {1478, 18968}, {1479, 12896}, {1498, 2935}, {1499, 2696}, {1506, 9697}, {1509, 2368}, {1531, 10296}, {1550, 36170}, {1553, 36172}, {1568, 3153}, {1593, 11439}, {1594, 9820}, {1599, 10132}, {1600, 10133}, {1619, 2063}, {1621, 2185}, {1633, 13397}, {1641, 10717}, {1649, 20404}, {1656, 9704}, {1657, 34584}, {1658, 18436}, {1691, 3231}, {1692, 3291}, {1698, 9587}, {1699, 9586}, {1793, 6326}, {1812, 26703}, {1853, 30744}, {1870, 19469}, {1897, 7452}, {1936, 23692}, {1946, 2714}, {1963, 19133}, {1971, 3289}, {1977, 18268}, {1992, 9084}, {2004, 21461}, {2005, 21462}, {2030, 9136}, {2051, 9562}, {2071, 2693}, {2072, 25739}, {2076, 8627}, {2106, 9455}, {2112, 2311}, {2175, 6015}, {2176, 35105}, {2177, 28559}, {2187, 29056}, {2193, 32726}, {2203, 2991}, {2223, 2711}, {2330, 5297}, {2341, 16554}, {2353, 28710}, {2365, 6514}, {2366, 3926}, {2382, 5009}, {2384, 3285}, {2393, 11416}, {2482, 11006}, {2644, 37135}, {2651, 3218}, {2682, 36174}, {2691, 3309}, {2692, 3667}, {2694, 6001}, {2700, 17209}, {2704, 8642}, {2705, 8643}, {2708, 37793}, {2709, 8644}, {2710, 18860}, {2717, 5536}, {2719, 23224}, {2720, 23189}, {2721, 16702}, {2723, 14956}, {2724, 14953}, {2725, 18206}, {2726, 5211}, {2727, 4091}, {2729, 6629}, {2740, 4786}, {2741, 26006}, {2746, 30234}, {2748, 6065}, {2754, 25083}, {2760, 3977}, {2769, 6332}, {2790, 36192}, {2794, 36163}, {2858, 14588}, {2859, 15413}, {2860, 7199}, {2861, 17139}, {2862, 30941}, {2863, 30939}, {2867, 3265}, {2868, 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13353}, {3699, 9059}, {3732, 4241}, {3746, 7343}, {3747, 12031}, {3763, 6698}, {3796, 5621}, {3815, 9604}, {3818, 5169}, {3819, 15246}, {3832, 11424}, {3845, 13482}, {3851, 15046}, {3868, 13739}, {3869, 14529}, {3877, 17512}, {3909, 4585}, {3917, 6030}, {3939, 4627}, {4074, 10328}, {4215, 29009}, {4235, 30247}, {4238, 26706}, {4239, 15988}, {4242, 30250}, {4273, 28317}, {4296, 19505}, {4414, 5197}, {4557, 4629}, {4559, 8687}, {4584, 5384}, {4590, 9150}, {4600, 8709}, {4602, 9065}, {4603, 30670}, {4625, 34083}, {5008, 31609}, {5020, 5422}, {5026, 5108}, {5033, 8617}, {5050, 5544}, {5055, 15088}, {5070, 20396}, {5085, 5646}, {5091, 24617}, {5092, 5650}, {5094, 7703}, {5102, 31860}, {5104, 9831}, {5107, 13192}, {5111, 20977}, {5133, 23292}, {5135, 37633}, {5137, 33129}, {5138, 14996}, {5170, 8649}, {5189, 29012}, {5235, 9093}, {5250, 37032}, {5254, 9603}, {5285, 38822}, {5320, 37685}, {5333, 9103}, {5398, 19245}, {5418, 9677}, {5446, 34484}, {5449, 14940}, {5463, 11612}, {5464, 11613}, {5477, 6388}, {5505, 8542}, {5548, 32686}, {5562, 7488}, {5587, 9621}, {5597, 13208}, {5598, 13209}, {5603, 11723}, {5606, 17404}, {5612, 6105}, {5616, 6104}, {5618, 9200}, {5619, 9201}, {5641, 9141}, {5649, 35909}, {5661, 38352}, {5840, 10767}, {5846, 32298}, {5886, 12261}, {5890, 6644}, {5891, 18475}, {5899, 13391}, {5907, 13367}, {5943, 12834}, {5946, 13358}, {5965, 32223}, {5994, 6137}, {5995, 6138}, {6003, 34961}, {6011, 9810}, {6032, 11187}, {6043, 32911}, {6070, 22104}, {6093, 14653}, {6102, 11561}, {6150, 15770}, {6153, 11536}, {6197, 12661}, {6198, 12888}, {6200, 35299}, {6214, 12804}, {6215, 12803}, {6225, 30552}, {6233, 13242}, {6236, 32228}, {6240, 22660}, {6243, 37440}, {6284, 12374}, {6353, 6515}, {6368, 30716}, {6396, 35300}, {6413, 10962}, {6414, 10960}, {6467, 34470}, {6516, 13395}, {6528, 18831}, {6561, 9676}, {6564, 35834}, {6565, 35835}, {6574, 7259}, {6583, 18180}, {6617, 15324}, {6638, 23606}, {6640, 23294}, {6642, 7592}, {6676, 37636}, {6677, 11245}, {6739, 36154}, {6777, 30465}, {6778, 30468}, {6795, 9159}, {6816, 18925}, {6997, 11427}, {7058, 17135}, {7085, 26911}, {7256, 8706}, {7341, 36277}, {7354, 12373}, {7391, 31383}, {7417, 10753}, {7465, 37659}, {7476, 10101}, {7482, 10098}, {7487, 15473}, {7502, 23039}, {7503, 15056}, {7517, 16266}, {7519, 31670}, {7526, 15058}, {7527, 11430}, {7533, 18427}, {7542, 31831}, {7550, 10170}, {7556, 37478}, {7574, 19381}, {7577, 18474}, {7583, 19052}, {7584, 19051}, {7605, 25555}, {7666, 33541}, {7669, 14060}, {7689, 21844}, {7708, 8585}, {7715, 11566}, {7724, 10902}, {7725, 11824}, {7726, 11825}, {7779, 19558}, {7796, 18796}, {7799, 35568}, {8024, 19571}, {8025, 9108}, {8029, 12064}, {8041, 10329}, {8057, 22239}, {8151, 14695}, {8154, 14889}, {8200, 12466}, {8207, 12467}, {8220, 12894}, {8221, 12895}, {8227, 9622}, {8286, 24916}, {8287, 24955}, {8371, 30220}, {8537, 12596}, {8550, 37648}, {8584, 20192}, {8651, 10425}, {8673, 10423}, {8675, 9060}, {8681, 32127}, {8683, 8698}, {8690, 23831}, {8691, 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11418}, {10537, 20243}, {10594, 11387}, {10601, 17809}, {10605, 15078}, {10610, 14128}, {10625, 12088}, {10627, 13564}, {10632, 10662}, {10633, 10661}, {10639, 32586}, {10640, 32585}, {10665, 10881}, {10666, 10880}, {10681, 11420}, {10682, 11421}, {10754, 25047}, {10766, 35901}, {10796, 12201}, {10942, 12905}, {10943, 12906}, {10989, 11645}, {11050, 15354}, {11078, 32461}, {11092, 32460}, {11107, 12528}, {11145, 13349}, {11146, 13350}, {11159, 11162}, {11176, 36255}, {11186, 13170}, {11199, 32437}, {11204, 35493}, {11248, 12381}, {11249, 12382}, {11250, 18439}, {11270, 33556}, {11328, 11842}, {11381, 12086}, {11423, 15024}, {11426, 15465}, {11499, 12334}, {11550, 31074}, {11559, 18364}, {11585, 12419}, {11656, 12243}, {11704, 34114}, {11793, 37126}, {11805, 15800}, {11820, 21312}, {11822, 12365}, {11823, 12366}, {11826, 12371}, {11827, 12372}, {11828, 12377}, {11829, 12378}, {11849, 35195}, {11898, 19154}, {12039, 29959}, {12068, 12079}, {12082, 37483}, {12084, 12290}, {12100, 22250}, {12113, 23240}, {12163, 32534}, {12225, 32330}, {12274, 12978}, {12275, 12979}, {12289, 18404}, {12293, 18504}, {12380, 15091}, {12588, 32243}, {12589, 32297}, {13015, 13055}, {13016, 13056}, {13163, 22051}, {13323, 16865}, {13348, 16661}, {13363, 15037}, {13364, 15038}, {13504, 15959}, {13509, 14961}, {13518, 19120}, {13558, 14687}, {13567, 19142}, {13582, 34306}, {13588, 15323}, {13596, 16194}, {13637, 13643}, {13757, 13762}, {13863, 30210}, {13935, 13969}, {13951, 13979}, {14008, 17188}, {14061, 15359}, {14133, 33021}, {14153, 20965}, {14247, 32027}, {14357, 36833}, {14360, 14928}, {14499, 14807}, {14500, 14808}, {14508, 36164}, {14528, 33537}, {14538, 34008}, {14539, 34009}, {14586, 32692}, {14590, 14696}, {14605, 35297}, {14606, 38366}, {14616, 24346}, {14651, 33511}, {14652, 34218}, {14658, 35006}, {14733, 21789}, {14781, 23105}, {14913, 21637}, {14933, 16169}, {14966, 26714}, {14981, 18337}, {14987, 37227}, {14998, 23969}, {15026, 32136}, {15028, 36752}, {15047, 22462}, {15069, 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{19478, 22758}, {19576, 36214}, {19924, 37901}, {20063, 29317}, {20301, 38317}, {20766, 20877}, {20987, 26284}, {20999, 36942}, {21008, 25435}, {21294, 23674}, {21444, 23216}, {21663, 37941}, {22135, 33652}, {22333, 22334}, {22528, 36982}, {22648, 33499}, {22649, 33501}, {23208, 28724}, {23235, 31854}, {23344, 28210}, {23390, 23861}, {23582, 32725}, {23698, 36181}, {23700, 35296}, {23832, 28218}, {23878, 36886}, {23964, 32687}, {23967, 36904}, {23997, 29055}, {24000, 36068}, {24041, 36066}, {24281, 30927}, {24542, 25536}, {24550, 29310}, {24987, 37152}, {25577, 28868}, {25738, 26917}, {26156, 26926}, {26227, 27958}, {26257, 35301}, {26733, 36075}, {26874, 26880}, {26875, 26886}, {26889, 27003}, {26890, 27065}, {26898, 37068}, {28624, 32656}, {28708, 36851}, {29181, 37900}, {29300, 37619}, {29330, 36015}, {29352, 35983}, {30212, 37964}, {30528, 32733}, {30715, 30717}, {31133, 36990}, {31378, 31379}, {31626, 32078}, {31874, 34209}, {32072, 32563}, {32073, 32570}, {32074, 32434}, {32124, 37969}, {32225, 37907}, {32262, 37485}, {32264, 34774}, {32267, 37909}, {32315, 32599}, {32428, 32439}, {32445, 32547}, {32515, 37906}, {32608, 37922}, {32640, 32681}, {32676, 32691}, {33543, 35446}, {33586, 37672}, {33852, 33883}, {33873, 33876}, {34146, 37929}, {34150, 36169}, {34380, 37897}, {34381, 37963}, {34382, 37777}, {34394, 36759}, {34395, 36760}, {34783, 37814}, {34830, 38535}, {35002, 37916}, {35056, 35057}, {35447, 38623}, {36034, 36064}, {36065, 36084}, {36070, 36142}, {36078, 36134}, {37496, 37924}, {37649, 37990}

▸ Functional Relations94 relations

Notes

X110 is the center of the Stammler hyperbola, SH, which is the rectangular hyperbola that passes through X1, X3, X6, X155, X159, X195, X399, X1498, X2916, X2917, X2918, X2929, X2930, X2931, X2935, X2948, X3511, the excenters, and the vertices of the tangential triangle. SH is the bianticevian conic of X1 and X6 and the antipedal-anticevian conic of X3. SH is the tangential isogonal conjugate of the Euler line, the tangential isotomic conjugate of the van Aubel line, the excentral isogonal conjugate of line X30X40, and the excentral isotomic conjugate of line X191X2938. SH is tangent to the Euler line at X3 and meets the line at infinity (and the Jerabek hyperbola, other than at X3 and X6) at X2574 and X2575. SH is the locus of a point P for which the P-Brocard triangle is perspective to ABC. (Randy Hutson, 9/23/2011, 1/29/2015)

J. W. Clawson, “Points on the circumcircle,” American Mathematical Monthly 32 (1925) 169-174.

Roland H. Eddy and R. Fritsch, “The conics of Ludwig Kiepert: a comprehensive lesson in the geometry of the triangle,” Mathematics Magazine 67 (1994) 188-205.

Benedetto Scimemi, “Paper-folding and Euler’s Theorem Revisited,” :cite:`Forum Geometricorum <forum-geometricorum>`.

Seven constructions from Randy Hutson, January 29, 2015:

  1. Let P be a point, other than X4, on Euler line. Let A' be the reflection of P in BC, and define B' and C' cyclically. The circumcircles of AA'B', BC'A', and CA'B' concur in X110.

  2. Let Q be a point on line X2X6 other than X2. Let A'B'C' be the cevian triangle of Q. Let A″ be the {B,C}-harmonic conjugate of A' (or equivalently, A″ = BC∩B'C'), and define B″, C″ cyclically. The circumcircles of AB″C″, BC″A″, CA″B″ concur in X110.

  3. Let La, Lb, Lc be the lines through A, B, C, resp. parallel to the Euler line. Let Ma, Mb, Mc be the reflections of BC, CA, AB in La, Lb, Lc, resp. Let A' = Mb∩Mc, and define B', C' cyclically. Triangle A'B'C' is inversely similar to, and 3 times the size of, ABC. Let A″B″C″ be the reflection of A'B'C' in the Euler line. The triangle A″B″C″ is homothetic to ABC, with center of homothety X125 and centroid X110. (See Hyacinthos #16741/16782, Sep 2008.)

  4. Let A', B', C' be the intersections of the Lemoine axis and lines BC, CA, AB, resp. The circumcircles of AB'C', BC'A', CA'B' concur in X110.

  5. Let A', B', C' be the intersections of line X36X238 and lines BC, CA, AB, resp. The circumcircles of AB'C', BC'A', CA'B' concur in X110.

  6. Let A', B', C' be the intersections of the Euler line and lines BC, CA, AB, resp. Let Oa, Ob, Oc be the circumcenters of AB'C', BC'A', CA'B', resp. The lines AOa, BOb, COc concur in X110.

  7. Let Na be the reflection of X5 in the perpendicular bisector of BC, and define Nb, Nc cyclically. X110 = X2070 of NaNbNc.

Let A2B2C2 and A3B3C3 be the 2nd and 3rd Parry triangles. Let A' be the barycentric product A2*A3, and define B' and C' cyclically. The lines AA', BB', CC' concur in X110. (Randy Hutson, February 10, 2016)

Let A'B'C' be the triangle described in ADGEOM #2697 (8/26/2015, Tran Quang Hung). A'B'C' is homothetic to the anticomplementary triangle at X110. The nine-point circle of A'B'C' touches the circumcircle of ABC at X110. Also, X110 = X125-of-A'B'C'. (Randy Hutson, Novermber 2, 2016)

Let A' be the trilinear pole of the perpendicular bisector of BC, and define B', C' cyclically. A'B'C' is homothetic to the circumanticevian triangle of X4 at X110. X110 is also the barycentric product A'*B'*C'. (Randy Hutson, January 29, 2018)

Let OA be the circle centered at the A-vertex of the AAOA triangle and passing through A; define OB and OC cyclically. Circles OA, OB, OC concur in X110. (Randy Hutson, August 30, 2020)

X110 is the {X5,X49}-harmonic conjugate of X54.