Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Interesting Geometry problem

  1. Jan 27, 2005 #1
    First of all note this is NOT HOMEWORK

    This is an interesting geometry problem my old statistics and discrete math teacher gave to me, i solved it, however i just wanted to give it out..... very tough problem (at least for me, probably easy for most poeple here)

    You have a triangle... the lengths of the three medians are
    Ma = 3
    Mb = 4
    Mc = 5

    so what is the area of the triangle?

    good luck
  2. jcsd
  3. Jan 27, 2005 #2

    I'm not a native english speaking person so I don't get the "median" part. Do you mean lenght of the sides?
  4. Jan 27, 2005 #3

    matt grime

    User Avatar
    Science Advisor
    Homework Helper

    No, he means the lengths of the medians which are the lines that pass from one corner to the mid point of the opposite sides. It isn't a particularly difficult question if you know how to describe the areas of triangles in terms of sides (at least on first inspection it seems there is an obvious argument to try).
  5. Jan 27, 2005 #4
    Let G be the barycenter of ABC, and let P be its symmetric point with respect to middle point of BC.

    Then, the triangle BGP is formed by 2/3 of the medians (and it is rectangle).

    So, BGParea = (2/3)^2 * (3*4)/2 = 8/3 .

    But BGP is 1/3 of ABC.

    So, ABCarea is 8.
    Last edited: Jan 27, 2005
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook