A rectangular field is to be fenced on three sides with 1000 m of fencing. The fourth side is a straight river's edge that will not be fenced. Find the dimensions of the field so that the area of the enclosure is 120000 square meters.

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