Description: Removing identical parts from the end of a line segment preserves congruence. Theorem 4.3 of Schwabhauser p. 35. (Contributed by Scott Fenton, 4-Oct-2013)
Ref | Expression | ||
---|---|---|---|
Assertion | cgrsub | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | simprl | |
|
2 | simprr | |
|
3 | simpl1 | |
|
4 | simpl21 | |
|
5 | simpl31 | |
|
6 | cgrtriv | |
|
7 | 3 4 5 6 | syl3anc | |
8 | simprrl | |
|
9 | simpl23 | |
|
10 | simpl33 | |
|
11 | cgrcomlr | |
|
12 | 3 4 9 5 10 11 | syl122anc | |
13 | 8 12 | mpbid | |
14 | 7 13 | jca | |
15 | simpl22 | |
|
16 | simpl32 | |
|
17 | brifs | |
|
18 | ifscgr | |
|
19 | 17 18 | sylbird | |
20 | 3 4 15 9 4 5 16 10 5 19 | syl333anc | |
21 | 1 2 14 20 | mp3and | |
22 | cgrcomlr | |
|
23 | 3 15 4 16 5 22 | syl122anc | |
24 | 21 23 | mpbid | |
25 | 24 | ex | |