This last related rates HW problem is givin me trouble for some odd reason.
A plane flying with a constant speed of 4 km/min passes over a ground radar station at an altitude of 11 km and climbs at an angle of 25 degrees. At what rate, in km/min is the distance from the plane to the radar station increasing 1 minutes later?
Law of Cosines:
The Attempt at a Solution
First using the law of cosines I found c at that particular moment.
Second I found the derivitive of the law of cosines
Working everything out I get:
I plug in c and get the wrong answer, what did I do wrong?