The circular cylinder described by the equation $x^2 + y^2 = 9$ and the plane described by the equation
$x - y - 3z = 0$ intersect to form the curve C. The curve C passes through the point P: $(x, y, z) =$
$(3, 0, 1)$.
(a) State a parametrization of the curve C. Be sure to include a domain for the parameter.
(b) Find a unit tangent vector to the curve C at the point P.