Gmail Calendar Documents Reader Web more »
Recently Visited Groups | Help | Sign in
Google Groups Home
Message from discussion 3-Points of a Triangle
The group you are posting to is a Usenet group. Messages posted to this group will make your email address visible to anyone on the Internet.
Your reply message has not been sent.
Your post was successful
 
From:
To:
Cc:
Followup To:
Add Cc | Add Followup-to | Edit Subject
Subject:
Validation:
For verification purposes please type the characters you see in the picture below or the numbers you hear by clicking the accessibility icon. Listen and type the numbers you hear
 
Ignacio Larrosa Caņestro  
View profile  
 More options Oct 27 2001, 11:22 am
Newsgroups: sci.math
From: ignacio.larr...@eresmas.net (Ignacio Larrosa Caņestro)
Date: 27 Oct 2001 08:22:34 -0700
Local: Sat, Oct 27 2001 11:22 am
Subject: Re: 3-Points of a Triangle
Ed Pegg Jr <e...@mathpuzzle.com> wrote in message <news:3BDA5A93.5030003@mathpuzzle.com>...

> You should visit the Encyclopedia of Triangle Centers.

> Currently, 1114 triangle centers are known.

> http://cedar.evansville.edu/%7Eck6/encyclopedia/

> --Ed Pegg Jr.

> Gerald Brown wrote:

> >    Here is a problem that I have been working on for awhile:

> >    A 3-point of a triangle is defined as a point where there exists
> > three distinct lines through the point and each line divides the
> > triangle into two polygons of equal area. Clearly, the centroid of the
> > triangle is a 3-point of the triangle. What percent of the area of a
> > triangle is the area of the set of 3-points of the triangle?

> >                                gdb

That problem it isnīt very concerned by the Encyclopedia of Triangle
Centers ...

It is known that the tangents to a hyperbola determine on the
asymptotes segments whose product is constant, and that the point of
tangencia T is the midpoint of the segment that the asymptotes
determine in the tangent.

Therefore the segments with ends in the sides to and b, that bisect to
the triangle, are tangent in their midpoints to a hyperbola that it
has to the sides to and b like asymptotes.

Calling X, Y and Z to medium the midpoints of the medians m_a, m_b and
m_c, such hyperbola is tangent to m_a in X and m_b in and.

The problem has 3 solutions if point R is inside tricuspoid XYZ
composed by three arcs of hyperbola that they have to each pair of
sides like asymptotes, 2 solutions on the own tricuspoid, excepted
points X, and and Z, and 1 in all the rest of the plane.

That is an affine problem, the ratio of the areas is invariant under
affine transformations. Therefore, it can be solved in any triangle
with full generallity. In an equilateral triangle, by example, or in
the triangle with vertices A(0, 0), B(1, 0) and C(0, 1). In any case,
it is easy, by
integration, to calculate the area of that tricuspoid.

Its area small is compared with the one of the triangle, exactly
(3*ln(2)-2)/4=0.01986... of the one of the triangle, less of a 2%.

P.S.: This is an automatic translate from Spanish. Let be indulgent
with the grammar ...

--
Saludos,

Ignacio Larrosa Caņestro
A Coruņa (Espaņa)
ignacio.larr...@eresmas.net
ICQ #94732648


    Reply to author    Forward  
You must Sign in before you can post messages.
To post a message you must first join this group.
Please update your nickname on the subscription settings page before posting.
You do not have the permission required to post.

Create a group - Google Groups - Google Home - Terms of Service - Privacy Policy
©2009 Google