(a)

The altitude of plane is  mi.

Plane is flying horizontally with a speed of  mi/h.

(b)

The rate at which distance from the plane to station is increasing.

(c)

Diagram of the situation at any time .

Here the actual distance from the station to the plane is considered as .

And horizontal distance from the station to the plane is considered as .

(d)

Apply Pythagorean theorem to  the figure.

Therefore,

.

(e)

Consider .

Differentiate on each side with respect to .

Plane is flying horizontally with a speed of  mi/h.

Thus, the rate .

From the part (d),

.

Here given that , distance from the plane to station is 2 mi.

Therefore, .

Substitute  in  .

Substitute ,  and   in equation (1).

Therefore, the rate at which distance from the plane to station is increasing is   mi/hr.

(a) The altitude of plane is  mi.

     Plane is flying horizontally with a speed of  mi/h.

(b)

The rate at which distance from the plane to station is increasing.

(c)

(d)

.

(e)

The rate at which distance from the plane to station is increasing is   mi/hr.