Please help me with this question

Inez has a phone card. the graph shows the number of minutes that remain on her phone card a certain number of days.

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

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.