Ahot air balloon rising vertically is tracked by an observer located 7 km7 km from the lift‑off point. at a certain moment, the angle between the observer's line of sight and the horizontal is ,π5, and it is changing at a rate of 0.2 rad/min.0.2 rad/min. how fast is the balloon rising at this moment? let yy be the height of the balloon (in km), be time (in minutes), and thetaθ the angle between the line‑of‑sight and the horizontal (in radians). (use decimal notation. give your answer to two decimal places.)