Allows Creativity of Solution Method

Because of the plethora of given information and the dynamic nature of Physlet problems, multiple solution methods are often available.  For example, the above problem could be solved correctly by...

-Looking to see where an incoming parallel ray crosses the principle axis.

-Placing the source where all rays leave the mirror parallel.

-Considering the source an object, measuring object and image distances, and using the lens equation.

-Finding R by finding the point where the rays converge on the source. f=R/2.