Results 1 to 2 of 2

Math Help - prove that triangle is equilateral

  1. #1
    Newbie
    Joined
    Sep 2011
    Posts
    12

    prove that triangle is equilateral

    In tetrahedron ABCD altitudes AA', BB',CC',DD' intersects in one point. O is a centre of sphere circumscribed on ABCD.Prove that if DO is perpendicular to plane A'B'C' then triangle ABC is equilateral. Please hint.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member mathbyte's Avatar
    Joined
    Oct 2011
    Posts
    26

    Post Re: prove that triangle is equilateral

    Quote Originally Posted by greg1987 View Post
    In tetrahedron ABCD altitudes AA', BB',CC',DD' intersects in one point. O is a centre of sphere circumscribed on ABCD.Prove that if DO is perpendicular to plane A'B'C' then triangle ABC is equilateral. Please hint.
    A hint? Okay... if the altitudes of the tetrahedron all intersect in one point, what is that telling you about the tetrahedron?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. equilateral triangle
    Posted in the Trigonometry Forum
    Replies: 0
    Last Post: November 10th 2010, 02:07 AM
  2. Equilateral Triangle
    Posted in the Geometry Forum
    Replies: 1
    Last Post: November 1st 2010, 06:51 PM
  3. Equilateral Triangle
    Posted in the Geometry Forum
    Replies: 3
    Last Post: October 21st 2010, 05:37 AM
  4. Equilateral Triangle
    Posted in the Geometry Forum
    Replies: 0
    Last Post: October 15th 2010, 06:35 PM
  5. Equilateral Triangle
    Posted in the Geometry Forum
    Replies: 2
    Last Post: November 20th 2008, 03:13 PM

Search Tags


/mathhelpforum @mathhelpforum