1. The problem statement, all variables and given/known data A stone lies to the very edge at the bottom of a pool. The pool is filled with water to the top. The person standing three meters away from the pool is 1 meter tall and he can see exactly the half of the stone. Calculate the depth of the pool. 2. Relevant equations Snell's law: n * sin(x) = n2 * sin(y) 3. The attempt at a solution Okay.. Since I can see half of the stone, the angle should be 45 degrees, right? I should be able to calculate x degrees and therefore the bottom of the triangle (where he stands). With the bottom, I can calculate the bottom line of the triangle in the pool and then the depth. So I do that. sin(45) * 1.33 = 1.00 * sin(x) 1.33 is n for water. 1 is n for air. x = 70.05 degrees. So the inside of the triangle is approx 20 degrees. I use tan. tan 70 = 1/adjacent => 1/(tan 70) = adjacent => 0.36397. So the bottom of that triangle is 0.36397 meters, but that doesn't make sense, it should be atleast 3 meters because he is standing that far away from the pool. What am I doing wrong?