Answer:
10.69
Step-by-step explanation:
We must first know that the angle of refraction is given by the following equation:
n_water * sin (A_water) = n_air * sin (A_air)
where n is the refractive index, for water it is 1.33 and for air it is 1.
The angle (A) in the air is 22.8 °, and that of the water is unknown.
Replacing these values we have to:
1.33 * sin (A_water) = 1 * 0.387
sin (A_water) = 1 * 0.387 / 1.33
A_water = arc sin (0.2907) = 16.9 °
now for the tank depth:
h = D / tan (A_water)
D = 3.25
Replacing
h = 3.25 / tan 16.9 °
h = 10.69
Therefore the depth is 10.69 meters.
