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Hyacinthos · We discuss themes on Triangle Geometry

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  • Members: 391
  • Category: Geometry
  • Founded: Dec 22, 1999
  • Language: English
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Lemoine point   Message List  
Reply Message #1 of 21025 < Prev |

Dear triangle geometers,

I'm sure I speak for many who thank Antreas for establishing
Hyacinthos@onelist.

Antreas mentioned that that name Hyacinthos honors E. Lemoine, of whose
full name Hyacinthe is a part. The Lemoine point is often called the
symmedian point. In Ross Honsberger's Episodes in Nineteenth and Twentieth
Century Euclidean Geometry (Mathematical Association of America, 1995), a
whole chapter is devoled to this point.

However, Honsberger doesn't mention (directly) a certain interesting
property of the Lemoine point. For any point P, let A'B'C' denote the
pedal triangle of P (i.e., A' is the point in which the line through P
perpendicular to line BC meets line BC). Let S(P) be the vector sum
PA'+PB'+PC'. Then S(P) is the zero vector if P is the Lemoine point.

I conjecture that the converse is true: that if P is a "point" (i.e.,
f(a,b,c) : g(a,b,c) : h(a,b,c)) such that S(P)=0, then P = a^2 : b^2 : c^2
(barycentric coordinates of the Lemoine point).

By the way, many other vector sums involving triangle centers will be
included in ETC (Encyclopedia of Triangle Centers), which should appear
sometime before March 1, 2000.

Best holiday regards to all.

Clark Kimberling








Wed Dec 22, 1999 8:45 pm

ck6@xxxxxxxxxx.xxxx
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Message #1 of 21025 < Prev |
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Dear triangle geometers, I'm sure I speak for many who thank Antreas for establishing Hyacinthos@onelist. Antreas mentioned that that name Hyacinthos honors E....
Clark Kimberling
ck6@xxxxxxxxxx.xxxx Send Email
Dec 22, 1999
8:45 pm

Dear all, Let me start in a similar way as Clark did, and thank Antreas for coining the idea to start a discussion list and then finding a good way to really...
Floor van Lamoen
f.v.lamoen@xxx.xxx Send Email
Dec 23, 1999
8:23 am

... Of course that is an equivalent property. ... [snip] ... It wasn't apparent to me either. However, the calculations are not difficult, and this converse is...
Barry Wolk
wolkb@xx.xxxxxxxxx.xxx Send Email
Dec 28, 1999
12:34 am
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