In the setting of Exercise 19, let be the angle that the line through the radar

In the setting of Exercise 19, let θ be the angle that the line through the radar station and the plane makes with the horizontal. How fast is θ changing 12 min after the plane passes over the radar station?

Data From Exercise 19

At a given moment, a plane passes directly above a radar station at an altitude of 6 km.

The plane’s speed is 800 km/h. How fast is the distance between the plane and the station changing half a minute later?

How fast is the distance between the plane and the station changing when the plane passes directly above the station?