Why is line segment ab = line segment ab? what is the name of the reason/postulate/whatever it is called?

Also, if you know that you have 2 triangles and you are trying to prove they are congruent and you know that 2 sides are equal and 1 angle is equal, which reason/law/postulate do you cite?

Thank you!

2. Originally Posted by e-mom
Why is line segment ab = line segment ab? what is the name of the reason/postulate/whatever it is called?

Also, if you know that you have 2 triangles and you are trying to prove they are congruent and you know that 2 sides are equal and 1 angle is equal, which reason/law/postulate do you cite?

Thank you!
$\displaystyle AB=AB$
Called the Reflexsive Postulate.

When two triangles have the same sides and and included angle they are congruent. This is called S.A.S. which means SIDE ANGLE SIDE. With ANGLE in between SIDE and SIDE, which was required.

Thank you!

4. geometry help needed, again

If you have 2 line segments, which form the 2 sides of a traingle, and have been given the fact that corresponding segments of the sides are equal, what rule could you cite to prove that the entire length of the 2 sides are the same.

I am eventually trying to prove that the triangle is isosceles.

A diagram is attached.

Thanks!

5. The way how I understand the problem there is no way to prove what you are saying because it is wrong.
I understand it as that you know the small one is isoseles and and to show the big one is also isoseles but there is not enough infromation.

Perhaps you wanted to say that line down the middle is a bisector?

6. thanks

Thank you for the info that my reasoning wasn't going to prove it that way. I'll look for another way.

Thank you!