Results 1 to 2 of 2

Math Help - triangles from pentagons

  1. #1
    Newbie
    Joined
    May 2010
    Posts
    3

    Post triangles from pentagons

    Hi. XD

    1. a regular pentagon is divided into three triangles. calculate all the angles in each of the triangles.[/B] (a picture of the pentagon described above is attached). please explain too.

    (the following info is relevant for the next 2 questions. btw the info the image of the pentagon is still relevant.)
    the middle triangle in the pentagon has all acute angles and the left triangle has an obtuse angle. we will can a triangel type A if it is similar to the middle triangle MJL. we will call a triangle type B if it is similar to the left triangle MNJ.

    2. show that a type A triangle can be divided into two triangles so that one is type A and the other is a type B

    3. show that a regular pentagon can be divided into 2010 triangles so that one is a type A and 2009 of them are type B

    Merci!
    Joyousness
    Attached Thumbnails Attached Thumbnails triangles from pentagons-2.-.jpg  
    Last edited by joyousness; May 10th 2010 at 01:21 AM. Reason: i missed part of the question
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Rhymes with Orange Chris L T521's Avatar
    Joined
    May 2008
    From
    Chicago, IL
    Posts
    2,844
    Thanks
    3
    Quote Originally Posted by joyousness View Post
    Hi. XD

    1. a regular pentagon is divided into three triangles. calculate all the angles in each of the triangles.[/B] (a picture of the pentagon described above is attached). please explain too.

    (the following info is relevant for the next 2 questions. btw the info the image of the pentagon is still relevant.)
    the middle triangle in the pentagon has all acute angles and the left triangle has an obtuse angle. we will can a triangel type A if it is similar to the middle triangle MJL. we will call a triangle type B if it is similar to the left triangle MNJ.

    2. show that a type A triangle can be divided into two triangles so that one is type A and the other is a type B

    3. show that a regular pentagon can be divided into 2010 triangles so that one is a type A and 2009 of them are type B

    Merci!
    Joyousness
    The fact that (the years) "2010" and "2009" appear in the problem hint to us that this question may be from a maths competition.

    This thread will remain closed as we conduct further investigation (we have zero tolerance for cheaters!!). If everything ends up being OK, it will be reopened.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. geometry - pentagons
    Posted in the Geometry Forum
    Replies: 3
    Last Post: June 24th 2010, 04:39 AM
  2. angles in pentagons
    Posted in the Geometry Forum
    Replies: 1
    Last Post: May 11th 2010, 03:21 AM
  3. Replies: 2
    Last Post: April 2nd 2010, 01:14 AM
  4. Replies: 1
    Last Post: February 16th 2008, 10:04 AM

Search Tags


/mathhelpforum @mathhelpforum