Please help me

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

Parallelogram efgh is a rectangle. he = 6, and fe = 8. find ge: and find fj:

The perimeter of a quarter circle is 14.28 miles. what is the quarter circle's radius?