# Thread: How do I do this proof?

1. ## How do I do this proof?

Given: Triangle ABC is isosceles with AC congruent to BC.
AC is extended to D.

2. ## Re: How do I do this proof?

Originally Posted by moriparty

Given: Triangle ABC is isosceles with AC congruent to BC.
AC is extended to D.

I do not know your axiom set or theorem sequence.
If you can show the measures, $\displaystyle m(\angle DAB) < m(\angle DBA)$ then there is a theorem that gives you that result.

3. ## Re: How do I do this proof?

It's Problem #3 on page 2:
http://stuy.enschool.org/pdf/forms/c...ms/MG21_11.pdf

Does this help?

4. ## Re: How do I do this proof?

Originally Posted by moriparty
It's Problem #3 on page 2:
http://stuy.enschool.org/pdf/forms/c...ms/MG21_11.pdf
Does this help?
Of course it does not help. That does not give a detailed list of axioms nor a detailed list of theorems.

I gave you the general solution. There is usually a theorem that states: In a triangle, if two angles have different measures then the longer side is opposite the larger angle. Now there are all sorts of ways to prove that. BUT each way depends upon the particular axiom set in use. We have no way to know that.

5. ## Re: How do I do this proof?

We have no way to know that.

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