# Thread: Did I do the following two column proof correctly?

1. ## Did I do the following two column proof correctly?

Here' what I came up with:

Given: $\displaystyle \angle SRT = \angle STR$; $\displaystyle \angle 3 = \angle 4$
Prove: $\displaystyle \angle 1 = \angle 2$

Statements:
1. $\displaystyle \angle SRT = \angle STR$; $\displaystyle \angle 3 = \angle 4$

2. $\displaystyle \angle 1 + \angle 3 = \angle SRT$; $\displaystyle \angle = 2 + \angle 4 = \angle STR$

3. $\displaystyle \angle 1 + \angle 3 = \angle 2 + \angle 4$

4. $\displaystyle \angle 1 = \angle 2$

Reasoning:
1. Given

4. Substitution

Am I right?

2. All the steps I added have red numbers. The things I changed are in red as well.

Statements:
1. $\displaystyle \angle SRT = \angle STR$; $\displaystyle \angle 3 = \angle 4$

2. $\displaystyle \angle 1 + \angle 3 = \angle SRT$; $\displaystyle \angle 2 + \angle 4 = \angle STR$

3. $\displaystyle \angle 2+\angle 4=\angle SRT$

4. $\displaystyle \angle 1 + \angle 3 = \angle 2 + \angle 4$

5.
$\displaystyle \angle 1 +\angle 3 = \angle 2 +\angle 3$

6. $\displaystyle \angle 1 = \angle 2$

Reasoning:
1. Given

3.
Transitive property (or Substitution)

4. Transitive Property (or Substitution)

5. Substitution

6. Subtraction property of equality

3. To other helpers:

Does anyone else use the transitive property? Or was that just my teacher...

4. Originally Posted by Quick
Does anyone else use the transitive property?
I use "transitive" because "substitution" is not well-defined for me.