Can someone help me with this physics problem?

Question

A small light fixture is on the bottom of a swimming pool, 0.50 m below the surface. The light emerging from the water forms a circle on the still water surface. What is the diameter of this circle?

________m

Answer 1

Total internal reflection occurs at 48.6 degrees angle of incidence, so it's 1.13m across.

2 x 0.5 x tan48.6


Unless the light bulb is set well down in the fixture, in which case the design of the fixture would limit the diameter of the circle.