Question

On a calm, bright day, you're scuba diving in a deep lake (n = 1.33), 5.40 m from your sailboat. When you are 3.10 m below the surface, the top of the sailboat mast appears to you to be in a direction 40.0° from vertical. Calculate the height of the mast

So i draw the figure and i get a traingle at the bottom with sides 5.4 and 3.1 but that doesnt help with the triangle that involve the height of the mast. I use snell's law to get an angle for the top traingle but I cant go any further. Helppp.

From your point of view, the entire sky appears to be confined to a bright disk directly above you on the surface of the water. Determine the diameter of this circle

then i am lost on this one..