X3515–X3601

Euler Line Intercepts & Named Geometric Centers

Euler line intercepts of central lines (X3515–X3552), together with the Dosa, Pappus, Moses circumcircle/infinity, Don Quixote, Beltrami-Euler, Beltrami-Parry, Myakishev conic, Dixit, Odehnal, and Liu points (X3555–X3601).
< A B C >: Reference Triangle △ABC [ A B ]: Sideline AB (Base c = 1) ( A R_b ): Euclid I.22 Guide Circle (A) ( B R_a ): Euclid I.22 Guide Circle (B) [ B C ]: Sideline BC (Side a) [ C A ]: Sideline CA (Side b) circumcircle: Circumcircle of △ABC incircle: Incircle of △ABC nine_point_circle: Nine-Point Circle (Euler / Feuerbach Circle) { 2, 3 }: Euler Line A = Vertex A (0.0000, 0.0000) B = Vertex B (1.0000, 0.0000) R_b = Radius Point R_b (0.8571, 0.0000) R_a = Radius Point R_a (0.2857, 0.0000) C = Vertex C (0.6122, 0.5999) X_3 = CIRCUMCENTER (0.5000, 0.1021) X_1 = INCENTER (0.5714, 0.2333) X_5 = NINE-POINT CENTER (0.5561, 0.2489) X_2 = CENTROID (0.5374, 0.2000) X_3515 = EULER LINE INTERCEPT OF LINE X(154)X(185) (0.7099, 0.6513) X_3516 = EULER LINE INTERCEPT OF LINE X(64)X(184) (0.5766, 0.3025) X_3517 = EULER LINE INTERCEPT OF LINE X(154)X(389) (0.6463, 0.4848) X_3522 = EULER LINE INTERCEPT OF LINE X(8)X(165) (0.4776, 0.0433) X_3523 = EULER LINE INTERCEPT OF LINE X(35)X(390) (0.5160, 0.1440) X_3532 = INTERSECTION OF LINES X(6,1204) AND X(64,1620) (0.8270, -0.0750) X_3534 = EULER LINE INTERCEPT OF LINE X(154)X(2777) (0.4252, -0.0937) X_3536 = EULER LINE INTERCEPT OF LINE X(19)X(587) (0.9271, 1.2197) X_3542 = EULER LINE INTERCEPT OF LINE X(33)X(498) (0.6774, 0.5661) X_3554 = INTERSECTION OF LINES X(1)X(6) AND X(19)X(604) (0.6589, 0.3371) X_3556 = INTERSECTION OF LINES X(25)X(65) AND X(31)X(56) (0.4474, -0.5587) X_3561 = SS(sin A → cos A) OF X(595) (0.3823, -0.0152) X_3563 = 1st MOSES CIRCUMCIRCLE POINT (0.9328, 0.3724) X_3572 = INTERSECTION OF LINES P(6)U(6) AND P(8)U(8) (0.9934, -0.0218) X_3580 = INTERSECTION OF LINES X(2)X(6) AND X(30)X(74) (1.2481, 0.9637) X_3582 = INTERSECTION OF LINES X(1)X(2) AND X(11)X(30) (0.9342, 0.5888) A B C X3 X1 X5 X2 X3515 X3516 X3517 X3522 X3523 X3532 X3534 X3536 X3542 X3554 X3556 X3561 X3563 X3572 X3580 X3582 (a, b, c) = (5, 6, 7) | AB = 1

X3515–X3601 (Euler Line Intercepts & Named Geometric Centers) — 16 representative centers (from 87 in collection) constructed on acute reference triangle \((a, b, c) = (5, 6, 7)\) with unit baseline AB = \(1\).

X_3532 — INTERSECTION OF LINES X(6,1204) AND X(64,1620)

X3532INTERSECTION OF LINES X(6,1204) AND X(64,1620)

Let DEF be the cevian triangle of X69 and A' the center of the circle that passes through D and through points where the line EF cuts to the circumcircle, and define B' and C' cyclically. The lines AA', BB', CC' concur in X3532. (Angel Montesdeoca, October 30, 2019)
X_3557 — 1st PAPPUS POINT

X35571st PAPPUS POINT

X3557 was submitted and called the Pappus point by Roland Bacher (March 11, 2009); coordinates and the related point X3558 were found by Peter Moses (March 12, 2009).
X_3567 — DON QUIXOTE POINT

X3567DON QUIXOTE POINT

The other two Spanish Points are the Sancho Panza Point X3060 and the Miguel de Cervantes Point X143.
X_3568 — BELTRAMI-EULER POINT

X3568BELTRAMI-EULER POINT

Let P(2) and U(2) be the 1st and 2nd Beltrami points (as indexed at Bicentric Pairs, accessible using the Tables button at the top of ETC), and let P(40) and U(40) be the isogonal conjugates of P(2) and U(2), respectively. Then X3568 is the point of intersection of the lines P(2)P(40) and U(2)U(40). The name “Beltrami-Euler Point” signifies the fact that X3568 lies on the Euler line. See also X2966 and X3569. Contributed by Chris van Tienhoven, June 7, 2009.
X_3570 — INTERSECTION OF LINES P(6)U(8) AND P(8)U(6)

X3570INTERSECTION OF LINES P(6)U(8) AND P(8)U(6)

The points given by trilinears P(6) =\(b : c : a\) and U(6) =\(c : a : b\) are indexed at Bicentric Pairs (accessible using the Tables button at the top of ETC), and likewise for their isogonal conjugates P(8) =\(1/b : 1/c : 1/a\) and U(8) =\(1/c : 1/a : 1/b\). The bicentric pair of lines P(6)U(8) and P(8)U(6) concur in X3570. Contributed by Peter Moses, July 7, 2009..
X_3571 — INTERSECTION OF LINES P(6)P(8) AND U(6)U(8)

X3571INTERSECTION OF LINES P(6)P(8) AND U(6)U(8)

The points given by trilinears P(6) =\(b : c : a\) and U(6) =\(c : a : b\) are indexed at Bicentric Pairs (accessible using the Tables button at the top of ETC), and likewise for their isogonal conjugates P(8) =\(1/b : 1/c : 1/a\) and U(8) =\(1/c : 1/a : 1/b\). The bicentric pair of lines P(6)P(8) and U(6)U(8) concur in X3571. Contributed by Peter Moses, July 7, 2009.
X_3572 — INTERSECTION OF LINES P(6)U(6) AND P(8)U(8)

X3572INTERSECTION OF LINES P(6)U(6) AND P(8)U(8)

The points given by trilinears P(6) =\(b : c : a\) and U(6) =\(c : a : b\) are indexed at Bicentric Pairs (accessible using the Tables button at the top of ETC), and likewise for their isogonal conjugates P(8) =\(1/b : 1/c : 1/a\) and U(8) =\(1/c : 1/a : 1/b\). The pair of central lines P(6)U(6) and P(8)U(8) concur in X3572. Contributed by Peter Moses, July 7, 2009.
X_3576 — INTERSECTION OF LINES X_1X_3 AND X_2X_515

X3576INTERSECTION OF LINES X1X_3 AND X2X_515

Let Pa be the parabola with focus A and directrix BC, and define Pb and Pc cyclically. X3576 is the centroid of the six points of tangency of lines from X1 to Pa, Pb, and Pc. (Randy Hutson, December 2, 2017)
X_3581 — INTERSECTION OF LINES X_3X_6 AND X_30X_74

X3581INTERSECTION OF LINES X3X_6 AND X30X_74

Let A1B1C1 and A2B2C2 be the 1st and 2nd Ehrmann circumscribing triangles. Let A* be the crosssum of A1 and A2, and define B* and C* cyclically. The lines AA*, BB*, CC* concur in X3581.
X_3590 — 1st DIXIT POINT

X35901st DIXIT POINT

The radius of circle TA is |BC|/6, and the Kiepert angle (e.g., B-to-C-to-X3890) is arctan(2/3).
X_3591 — 2nd DIXIT POINT

X35912nd DIXIT POINT

This point is obtained in the manner of X3590 using the inward semicircles instead of outward.
X_3597 — 2nd ODEHNAL POINT

X35972nd ODEHNAL POINT

Let MA, MB, MC be the centers of the circles A″, B″, C″ used to construct X3596, respectively. Then the lines A-to-MA, B-to-MB, C-to-MC concur in X3597. For more, see the reference and sketch at X3596.
X_3598 — 1st LIU POINT

X35981st LIU POINT

Let OA be the circle passing through B and C, internally tangent to the incircle, and likewise for OB and OC. Let PA be the point where OA meets the incircle, and likewise for PB and PC. Let QA be the point of intersection of the tangents to the incircle at PB and PC, and likewise for PB and PC. Then X3598 is the perspector of the triangles PAPBPC and QAQBQC; this point is also X7-of-QAQBQC. This point and X3599 were discovered by Kang-Ying Liu of St. Andrew’s Priory School, Honolulu, Hawaii, during 2010.
X_3599 — 2nd LIU POINT

X35992nd LIU POINT

Let PAPBPC be as at X3598. Let TA be the point of intersection of the lines BPC and CPB. X3599 is the perspector of triangles PAPBPC and TATBTC.