Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Symmedian point -earliest reference in navigation
    From: Bill Lionheart
    Date: 2018 Oct 16, 19:12 +0100
    These days eaisiestvway to play is to use a program called  Geogeba ... You can mark as many triangle centres as you like and then drag around the vertices. 

    On Tue, 16 Oct 2018, 16:50 David Pike, <NoReply_DavidPike@navlist.net> wrote:

    Bill Lionheart

    An equilateral cocked hat with PLs from three equidistant sources 120 degrees apart must be every navigator’s dream.  In that case the incenter, centroid, and symmedian point would all be in the same place.  An interesting exercise on graph paper would be to take an equilateral triangle ABC and draw a line through C from the mid point of side AB.  Then move C backwards and forwards along that line to make a number of isosceles triangles.  Then note how the position of each of the new symmedian points moves with respect to the original centre point.  Would they move away from line AB, towards it, or stop the same distance away.  E.g. you might think that as C moves towards AB, the new SP must move towards AB, but AB is now the longest side, so how do you cope with that.  Similarly, as C moves away from AB, AB is now the shortest side, but the triangle is bigger.  It gives you a headache.  Fortunately, I’ve run out of A4 1/10” graph paper to try it.  DaveP

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    NavList is a community devoted to the preservation and practice of celestial navigation and other methods of traditional position-finding. We're a group of navigators, navigation enthusiasts and hobbyists, mathematicians and physicists, and historians interested in all aspects of navigation but primarily those techniques which are non-electronic.

    To post a message, if you are already signed up as a NavList member, start a new discussion or reply to any posted message and use your posting code (this is a simple low-security password assigned when you join). You may also join by posting. Your first on-topic messsage automatically makes you a member, and a posting code will be assigned and emailed to you for future posts.

    Uniquely, the NavList message boards also permit full interaction entirely by email. You can optionally receive individual posts or daily digests by email, and any member can post messages by email (bypassing the web site) by sending to our posting address which is "NavList@NavList.net". This functionality is similar to a traditional Internet mailing list: post by email, read by email, reply by email. Most members will prefer the web interface here for posting and replying to messages.

    NavList is more than an online community... more about that another day.

    © Copyright notice: please note that the rights to all messages and posts in this discussion group are held by their respective authors. No messages or text or images extracted from messages may be reproduced without the explicit consent of the message author. Email me, Frank Reed, if you have any questions.

    Join / Get NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site