Is my proof correct?

onesun0000

Junior Member
Joined
Dec 18, 2018
Messages
83
I tried to write a proof for this:

Given: [MATH]\overline{AC}\cong \overline{CE}[/MATH]; [MATH]D[/MATH] is the midpoint of [MATH]\overline{CE}[/MATH]Prove: [MATH]\frac{1}{2}AC=DE[/MATH]12969

Here's my two-column proof:
12970

Please tell me if I messed up something. Thank you.
 
Does writing just "AC" necessarily or always mean the length of [math]\overline{AC}[/math]?
 
Does writing just "AC" necessarily or always mean the length of [math]\overline{AC}[/math]?
As far as what I learned in school is concerned, we use big letters, without the overline, to mean the length of a segment.
 
I tried to write a proof for this:

Given: [MATH]\overline{AC}\cong \overline{CE}[/MATH]; [MATH]D[/MATH] is the midpoint of [MATH]\overline{CE}[/MATH]Prove: [MATH]\frac{1}{2}AC=DE[/MATH]View attachment 12969

Here's my two-column proof:
View attachment 12970
In a very general way, yes the ten steps are correct.
However, we do not know on which set of axioms the reasons are based.
It looks like the set of axioms used by Ed Moise. If so you should have used the ruler postulate somewhere.
 
In a very general way, yes the ten steps are correct.
However, we do not know on which set of axioms the reasons are based.
It looks like the set of axioms used by Ed Moise. If so you should have used the ruler postulate somewhere.

oh thank you. what I know about ruler postulate is that we can pair every point with a number and vise versa so the distance between two points paired with coordinates, for example, A and B, is absolute value of the difference between A and B ([MATH]|A-B|[/MATH] or [MATH]|B-A|[/MATH].) I don't know if that's possible to use in that proof, or it's actually possible? I'm not sure.
 
Top