Answer: 307.8 yards
Explanation:
Hi, since the situation forms a right triangle (see attachment) we have to apply the next trigonometric function.
Sin α = opposite side / hypotenuse
Where α is the angle of depression of the boat looking down to a submarine, the hypotenuse is the distance from the boat to the submarine, and the opposite side (x) is the distance between the submarine and the sea level:
Replacing with the values given:
Sin 38 = x/ 500
Solving for x
Sin 38 (500) =x
x= 307.8 yards
Feel free to ask for more if needed or if you did not understand something.