Final answer:
The distance of the airplane from the kilometer stone at an angle of depression θ can be found using the equation H = D * [tan(B) - 1]/[1 + tan(B)].
Step-by-step explanation:
In order to find the distance of the airplane from the kilometer stone at an angle of depression θ, we can use the trigonometric function tangent (tan). The correct equation is option (e) tan(θ) = [tan(B) - 1]/[1 + tan(B)].
Let's break down the equation: tan(θ) is equal to the distance from the airplane (H) divided by the distance between the airplane and the kilometer stone (D). So when we rearrange the equation, we get H = D * [tan(B) - 1]/[1 + tan(B)].
This equation gives us the correct distance.