Why Are Perpendicular Bisectors Used in Plane Mirror Diagrams?

[logearav]

Optics -- plane mirror

Homework Statement

Revered members,
Kindly see my attachment. I don't understand the role of dotted lines in the diagram. Actually , DA, EC and NB are perpendicular bisectors. In the first place, why should we draw perpendicular bisectors? Can't we solve the problem with incident ray and reflected ray alone? Please help, members.

Homework Equations

The Attempt at a Solution

 

[ehild]

The bisectors help you to draw the reflected ray, as it makes an angle with it equal to that of the incident ray.

ehild

 

[Villyer]

The perpendicular bisector is just the normal line to the mirror that creates the incident and reflected angles.

In this case I don't think they play a big role. This question seems more conceptual than anything.

 

[logearav]

Thanks for the replies ehild and Villyer. I got it now.