A Decision Theorem to Prove the Parallelism of Lines and Surfaces in Space

A Decision Theorem to Prove the Parallelism of Lines and Surfaces in Space

Definition of line and face parallel: Line and face do not have an intersection (line and face do not intersect).
Theorem: If a line is parallel to a line in another plane, the line is parallel to that plane.
Note: The word "other" indicates that the line and plane of the proof are disjoint.

What is the difference between a lens and a mirror

The lens was called a lens because the light that our eyes felt was refracted into our eyes through the lens.
A mirror was a situation where light didn't penetrate the mirror and a reflection was sensed by us.
The biggest difference between the two was the way the light spread. One was the refraction through the mirror, and the other was the reflection through the mirror.

A lens is called a lens because the light that our eyes feel is reflected through it.
A mirror is a condition in which light does not pass through the mirror and reflection is perceived by us.
The biggest difference between the two is the way light travels, one through the mirror refraction, the other is not through the mirror reflection.