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Homework help

  1. Dec 10, 2003 #1
    can anyone explain how to do this proof?
    Given: angle ABC is congruent to angle ABD, angle ACB is congruent to angle ADB
    Prove: triangle ACB is congruent to triangle ADB.
    thank you!
     
  2. jcsd
  3. Dec 10, 2003 #2

    NateTG

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    Do you have any theorems that you can use? Like the angle-side-angle theorem?

    If you have that, and you can show that BAD and BAC are the same, then you're done.
     
  4. Dec 10, 2003 #3
    yeah...i think i could use the ASA theorem...but i dunno how to explain it and when to use it.
     
  5. Dec 10, 2003 #4

    NateTG

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    You know that the sum of the interior angles of a triangle is always the same, right?
     
  6. Dec 10, 2003 #5
    yes.
     
  7. Dec 10, 2003 #6

    NateTG

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    So you know that:
    ABC + BCA + CAB = ABD + BDA + DAC

    from the problem you have:
    ABC=ABD
    and
    BCA=BDA

    so if you make the substitutions you get
    ABC+BCA+CAB=ABC+BCA+DAC

    ABD+BCA can be cancellet from both sides, so you get
    CAB=DAC
     
  8. Dec 10, 2003 #7
    oh...i get it now! thanx!
     
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