A viewer is in the point (2, 1, 4) and looks at the (y, z)-plane which is illuminated by a directional light source. The light source lies in infinite distance in the direction of the vector (1, 2,...

A viewer is in the point (2, 1, 4) and looks at the (y, z)-plane which is

illuminated by a directional light source. The light source lies in infinite distance in

the direction of the vector (1, 2, 3). At which point on the plane can the viewer see