A source of laser light is at point A on the ground between two parallel walls. The walls are perpendicular to the ground. AB is a ray of light which strikes the wall on the left at point B which is 60 meters above the ground. AC is a ray of light which strikes the wall on the right at point C which is 40 m above the ground. The ray AB makes an angle of 60 degrees with the ground. The ray AC makes an angle of 30 degrees with the ground.