Please can someone help me solve the question in the picture 10 points plus brainliest!!!

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

Acircle has a radius of 12.6cm what is the exact length of an arc formed by a central angle measuring 120

Maria solved an equation as shown below. what is the solution to maria’s equation?