Suppose that a reflected light wave has an angle of reflection of 30°. what must be the angle of incidence and what must be the angle between the reflecting surface and the incoming wave? explain.

For the angle of reflection to be 30°, the angle of incidence must be 30°, too, because these two angles are always equal. So the angle between an imaginary line perpendicular to the surface of the barrier and the incoming wave must be 30°. For this to happen, the angle between the surface of the barrier and the incoming wave must be

90° – 30° = 60°.

Hope this helps.

Tobey

whichever one it is, it's definitely not one that you included on the list you provided.