# Did I do the following two column proof correctly?

• Jul 3rd 2007, 06:42 PM
icebreaker09
Did I do the following two column proof correctly?
Attachment 3487

Here' what I came up with:

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

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

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

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

4. $\angle 1 = \angle 2$

Reasoning:
1. Given

4. Substitution

Am I right?
• Jul 3rd 2007, 07:28 PM
Quick
All the steps I added have red numbers. The things I changed are in red as well.

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

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

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

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

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

6. $\angle 1 = \angle 2$

Reasoning:
1. Given

3.
Transitive property (or Substitution)

4. Transitive Property (or Substitution)

5. Substitution

6. Subtraction property of equality
• Jul 3rd 2007, 07:30 PM
Quick
To other helpers:

Does anyone else use the transitive property? Or was that just my teacher...
• Jul 3rd 2007, 07:45 PM
ThePerfectHacker
Quote:

Originally Posted by Quick
Does anyone else use the transitive property?

I use "transitive" because "substitution" is not well-defined for me. :D