Results 1 to 2 of 2

Math Help - Determining the Top triangle of a Pentagram

  1. #1
    Newbie
    Joined
    May 2013
    From
    Canada
    Posts
    22

    Determining the Top triangle of a Pentagram

    Hello genii,

    I bet this will stump you,

    Given 5 outer points (x,y) of a five sided star:

    -23.0000 17.3200
    -11.3676 24.2994
    -33.3421 26.0574
    -11.6912 16.0979
    -17.4368 26.5549

    and 5 inner points of the pentagon within it:

    -18.4540 24.8663
    -19.2453 19.5728
    -16.4195 24.7036
    -21.1226 20.4364
    -15.0000 22.1200

    I want to determine the outer point that is opposite the pentagon corner angle that is closest to 90 degrees. In other words, I want the outer point of the triangle that makes the pentagon resemble a diamond.

    How do I do that using formulae?
    Last edited by Stockgoblin; June 16th 2013 at 03:39 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Sep 2012
    From
    Australia
    Posts
    3,802
    Thanks
    657

    Re: Determining the Top triangle of a Pentagram

    Hey Stockgoblin.

    Hint: The equation for a line in 2D is y = mx + b and two lines are perpendicular if m1*m2 = -1.

    Now you need to just get the equations for two perpendicular lines using your constraints and solve for the m's and b's.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 4
    Last Post: May 6th 2011, 08:55 AM
  2. Pentagram Puzzle
    Posted in the Math Puzzles Forum
    Replies: 1
    Last Post: April 21st 2009, 09:47 AM
  3. Find the measures of angles of pentagram?
    Posted in the Geometry Forum
    Replies: 4
    Last Post: February 15th 2009, 10:49 AM
  4. pentagram geometry
    Posted in the Geometry Forum
    Replies: 2
    Last Post: August 29th 2008, 03:41 AM
  5. Determining how many Circles fit in a Triangle
    Posted in the Advanced Math Topics Forum
    Replies: 7
    Last Post: November 21st 2005, 11:55 AM

Search Tags


/mathhelpforum @mathhelpforum