Math question! Need help, please

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

Rewrite the following quadratic functions in intercept or factored form. show your work. y = 9 + 12x + 4x^2

Given: circle o, cd is diameter, chord ab || cd. arc ab = 74°, find arc ca.