Results 1 to 4 of 4

Math Help - triangle

  1. #1
    Member helloying's Avatar
    Joined
    Jul 2008
    Posts
    177

    triangle

    Help Help! see picture attached.
    Attached Thumbnails Attached Thumbnails triangle-img001.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by helloying View Post
    Help Help! see picture attached.
    Similarity:

    \angle BOA = \angle COA

    90^o - \angle BAO = \angle OBA = \angle OAC

    \angle OAB = \angle OCA
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by helloying View Post
    Help Help! see picture attached.
    As angles BAC and BDA are right angles angle BAD is congrunet to to angle ACD (amoung other reasons because triangles BAD and BAC are both right and have a common angle other than the right angle)

    Hence triangles ABD and CAD are both right triangles and another pair of congruent andgles and so are similar.

    Part (b) you do by forming ratios of corresponding sides of two of the similar triangles.

    Part (c) yuo use the result of part (b) and Pythogoras' theorem to find AD, then the area is (1/2)AD.BD and BD is given.

    RonL
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by helloying View Post
    Help Help! see picture attached.
    Let AO = x. Since the triangles are similar you have the following equality of side ratios: \frac{4}{x} = \frac{x}{9} ....

    It should be simple to get the area now.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: April 23rd 2011, 08:10 AM
  2. Replies: 3
    Last Post: April 30th 2009, 07:41 AM
  3. Replies: 1
    Last Post: October 28th 2008, 07:02 PM
  4. Replies: 7
    Last Post: July 19th 2008, 06:53 AM
  5. Replies: 27
    Last Post: April 27th 2008, 10:36 AM

Search Tags


/mathhelpforum @mathhelpforum