1. C
from (1) we can't determine the circumference.
from (2) we don't know where the cord is located in the circle - the chord can be the diameter or smaller than the diameter.
from (1+2): we can determine that the chord is on a central angle of 60 degrees 360/6. The hight from the center of the circle (mark as: point k) to the chord divides the chord in to two straight triangles with a base of 3 (half of the chord's length). The angles of each triangle are 30:60:90, hence the hypotenuse equals 2*3=6=Radius.
2. B
There are three options to create a cylinder with a maximum volume, because there are 3 bases possible.
diameter=8, R=4, H=12, Volume=pi*R^2*H=pi*192
diameter=10, R=5, H=8, Volume=pi*R^2*H=pi*200
diameter=8, R=4, H=10, Volume=pi*R^2*H=pi*160
