The 180 Degree Rule

The 180 Degree Rule 
I have been giving the great honor to research the 180 degree rule.

 

Above is the 180 degree rule, where the cameras can be any where in the green area, but not in the red, otherwise it will confuse the audience as the two characters will be on the opposite side of each other.

Here is a video about the 180 degree angle, which shows where the camera can be put, and also some examples of some camera shots: 

To see another example of this, click here.