Compute the unit vector k for the axis of rotation and the angle of rotation about k to achieve this rotation matrix.
a) k = 1/√(3)[1,1,1], θ = 60°
b) k = 1/√(2)[1,0,1], θ = 45°
c) k = 1/√(2)[0,1,0], θ = 90°
d) k = 1/√(3)[1,0,1], θ = 30°