A painter needs to buy a ladder in order to paint a wall that is 18 feet high. In order to ensure the ladder does not fall it needs to be placed 3 feet away from the wall. What size ladder does the painter need to buy to ensure that he will be able to paint the highest point of the wall? Write your answer rounded to the ncarest tenth.​

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