I am performing an analysis for optical ray traces on a SolidWorks 2014 drawing. I am looking to find the perfect position of a mirror so that it will reflect a laser across a specific plane. Since the reflected angle off of a mirror surface equals the incident angle I have two angle dimensions that I have to manipulate to see the results of rotating the angle of the mirror surface. Is there a way that I can have the reflected angle dimension always equal the incident angle dimension using an equation?

When sketching, you could place a construction line between the two lines, and place a Symmetric relationship. That way both lines would maintain the same angle off the construction line. In the screenshot below, the dimension on the left is driven by the dimension on the right.