Really need

a 20 foot ladder touches a building 16 feet up the wall. what is the measure of the angle the ladder makes with the ground?

which expression has a value of 1?
a. sinx+cosx
b. sin2x-cos2x
c. sin2x+cos2c
d. (sinx+cosx)2

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