Classify a line relative to a plane before solving

Determine whether each line intersects the plane at a unique point, lies on it, or does not intersect it. If there is a unique intersection, find that point and the angle between the line and plane. All parameters are real.

(a) $\Pi:\mathbf r\cdot(2,1,-3)=5$, $l:\mathbf r=(3,-1,1)+\lambda(-2,1,-3)$.

(b) $\Pi:\mathbf r\cdot(2,1,-3)=5$, $l:\mathbf r=(2,1,0)+\lambda(1,1,1)$.