# Coxeter- Theorem 2.23

- Author:
- AndrewLyon

- Topic:
- Geometry

2.23 -

*If two lines have a common point, they are coplanar.*PROOF. If two lines have a common point*C*, we may name them*AC*,*BC*, and conclude that they lie in the plane*ABC*.- Author:
- AndrewLyon

- Topic:
- Geometry

2.23 - *If two lines have a common point, they are coplanar.*
PROOF. If two lines have a common point *C*, we may name them *AC*, *BC*, and conclude that they lie in the plane *ABC*.