Clark Kimberling wrote on February 25, 2000 ... Dear Clark and all, Incircle-inverses are most of time complicated in barycentric coordinates as Paul Yiu...
454
John Conway
conway@...
Mar 2, 2000 5:50 pm
... Let me rewrite this so that I can see it: ( xx(yy-zz)[(cc-bb)yyzz + bbzzxx - ccxxyy] : : ) = ( xx(yy-zz)[ccyy(zz-xx) + bbzz(xx-yy)] : : ) = ( ccXY + bbZX...
455
Jean-Pierre.EHRMANN
Jean-Pierre.EHRMANN@...
Mar 3, 2000 10:06 am
... De : "John Conway" <conway@...> À : <Hyacinthos@onelist.com> Cc : <Hyacinthos@onelist.com> Envoyé : jeudi 2 mars 2000 18:42 Objet : Re:...
457
John Conway
conway@...
Mar 3, 2000 4:19 pm
... - you happen to have used it! - ... Is M a general point, or some particular one? ... The standard term is "circular points at infinity" ... Very nice -...
458
Floor van Lamoen
f.v.lamoen@...
Mar 3, 2000 4:43 pm
Dear Hyacinthos members, First of all, thanks to all of you who have sent me and Lyanne their congratulations. Our daughter, Nuriye, is a nice healthy baby,...
459
John Conway
conway@...
Mar 3, 2000 6:09 pm
Just before travelling to Puerto Rico for a week, I spent a pleasant evening with Lawrence Evans discussing triangle geometry. I promised him that I'd work out...
460
John Conway
conway@...
Mar 3, 2000 6:19 pm
... Please call this the "extra-Gergonne point"! The prefix "ex-" has been used in the past both for harmonic associates (for which Steve and I propose to keep...
462
Barry Wolk
wolkb@...
Mar 3, 2000 9:20 pm
First some definitions: ... OK, I will use the term "cevian circumcircle" of a point P for the circle passing through the three cevian points of P. For P =...
463
xpolakis@...
Mar 5, 2000 3:43 am
... Dear Jean-Pierre.and All, I think that we can ask more loci questions: The pedal circle of a point P is the circle passing through the feet A',B',C' of the...
464
Jean-Pierre.EHRMANN
Jean-Pierre.EHRMANN@...
Mar 6, 2000 12:12 am
... De : "John Conway" <conway@...> À : <Hyacinthos@onelist.com> Cc : "Hyacinthe" <Hyacinthos@onelist.com> Envoyé : vendredi 3 mars 2000 17:10...
465
John Conway
conway@...
Mar 6, 2000 3:09 am
Erect "isosceles Napoleons" - that is to say, isosceles triangles of the same base angle x - on the edges of ABC. The typical vertex is Bx = ( SC+Sx : -bb :...
466
xpolakis@...
Mar 6, 2000 10:54 am
In the following book: Geometrie I Herausgegeben von Dr. De Vries Studienrat an der Leibnizschule Hannover Unter Mitwirkung von Fricke-Heiland-Oppermann Georg...
467
Steve Sigur
ssigur@...
Mar 7, 2000 4:12 am
... ........[snip] I want to bring John up to date on what we did last holiday season. I think we accomplished good things back then and I want him to know ...
468
Jean-Pierre.EHRMANN
Jean-Pierre.EHRMANN@...
Mar 7, 2000 5:31 pm
... De : "Barry Wolk" <wolkb@...> À : <Hyacinthos@onelist.com> Envoyé : vendredi 3 mars 2000 22:20 Objet : [EMHL] Re: Proofs of Feuerbach theorem...
469
John Conway
conway@...
Mar 7, 2000 10:59 pm
... The point of my most recent letter was that this is one of many statements that are subsumed in a much grander generalization: in general the line Px Py...
470
Paris Pamfilos
pamfilos@...
Mar 8, 2000 11:37 am
Does anyone knows a good reference for the billiard ball problem inside a triangle? P. Pamfilos...
471
Paul Yiu
yiu@...
Mar 8, 2000 1:50 pm
Dear friends, A pdf version of this message can be found at http://www.math.fau.edu/yiu/hyacinthos000308.pdf ************ In response to Antreas' question...
472
arnaud.pascal@...
Mar 8, 2000 3:42 pm
Hello every body ... I give you my references about billiards - Francois Rouviere Petit Guide de Calcul Differentiel Cassini, 1999 - 180 FF - ISBN...
473
xpolakis@...
Mar 8, 2000 5:05 pm
... .... and what is that problem, Paris? The Billiard problem I konw is that one with the sphere (ball) inside a circle (or an ellipse), called Alhazen...
474
xpolakis@...
Mar 8, 2000 5:13 pm
An Oxford mathematician, Dr Peter Neumann (pictured above), has `solved' a 2,000-year-old problem-perhaps the last of the great problems of the classical...
475
xpolakis@...
Mar 8, 2000 5:39 pm
Dear Paul, Thanks for your message. Here is another 9PC problem I don't remember having discussed it: In the orthocentric tetrad H,A,B,C the...
476
Ignacio Larrosa Ca...
ilarrosa@...
Mar 8, 2000 7:26 pm
... From: Paris Pamfilos <pamfilos@...> To: <Hyacinthos@onelist.com> Sent: Wednesday, March 08, 2000 12:46 PM Subject: [EMHL] Billiard ball ... ?Have...
477
xpolakis@...
Mar 8, 2000 7:29 pm
The third presentation below is on AlHazen's problem (and the 2nd on cubics) ... Friday, March 6, 1998 Special Session on Geometry I Friday 2:45-4:40 pm ...
478
xpolakis@...
Mar 8, 2000 8:21 pm
... Neumann, Peter M.: Reflections on reflection in a spherical mirror. Am. Math. Mon. 105, No.6, 523-528 (1998). The author considers Alhazen's Billiard...
479
Tony Mann
A.Mann@...
Mar 9, 2000 7:42 am
... Somewhat inappropriately, this article appeared in the Daily Telegraph (London) on 1st April (1997?). But it wasn't a hoax! Tony Tony Mann School of...
480
Barry Wolk
wolkb@...
Mar 9, 2000 8:40 pm
... Yes, that's what desmic means, 12 points, 16 lines, etc. But John Conway once remarked that the planar desmic configurations are more general than just the...
481
Paul Yiu
yiu@...
Mar 9, 2000 9:54 pm
Dear Antreas, It was a surprise to find my own name in your message about the billiard ball. I remember the interesting lecture Sam Sakmar gave 2 years ago on...
482
Jean-Pierre.EHRMANN
Jean-Pierre.EHRMANN@...
Mar 10, 2000 1:14 am
... De : "Paul Yiu" <yiu@...> À : <Hyacinthos@onelist.com> Envoyé : mercredi 8 mars 2000 14:50 Objet : [EMHL] Cevian circumcircles tangent to the...
483
xpolakis@...
Mar 10, 2000 8:27 pm
Geometry Conference Recent Trends in Geometry and Symmetry A Conference in Honor of Donald W. Crowe Donald W. Crowe has spent over 40 years popularizing,...
484
Michael Keyton
mikeyton@...
Mar 11, 2000 1:46 am
Today in my 2nd year geometry class, we were proving that the Clawson point (X19) lies on the Euler line. One of the students asked about the locus of the...
