1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Finding a side length in similar triangles?

  1. Feb 6, 2012 #1
    Side note: PF is awesome! This is kind of like Tutor.com, only it's free and others can contribute their answers.

    1. The problem statement, all variables and given/known data
    Explain why triangle ABD is similar to triangle ABC and then find the length of side AB. Angles B and C are congruent. m(ADB)+m(BDC) = 180 degrees. AD=4 and DC=12.

    2. Relevant theorems, postulates, properties, etc.
    Corresponding parts of similar angles are similar.
    Symmetric property of similarity - if XYZ is similar to ABC, then XZY is similar to ACB, ZXY is similar to CAB, etc.

    3. The attempt at a solution
    The similarity ratio is 4:16 (side length in ABD:side length in ABC).I know that. If I knew at least one side length I could easily figure out what AB is. The problem is I don't.
  2. jcsd
  3. Feb 6, 2012 #2


    Staff: Mentor

    It would be helpful if you could post a screen shot or sketch of the two triangles.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook