It is important to label all your variables and expressions clearly because: a. it will help you get your equations set up correctly
b. it will check your answers
c. it will solve a system of equations
d. it will allow you to find definitions better

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters