law of cosines ...
A plane flying with a constant speed of 5 km/m passes over a ground radar station at an altitude of 1 km and climbs at an angle of 30 degrees. At what rate is the distance from the plane to the radar station increasing a minute later?
First of all, I don't know how to determine the sides using the given information. I'm thinking the base of the triangle, but, the triangle doesn't have enough information to solve for it.
Can I assume the red line bisects the rectangle or not? Otherwise, I don't see what else I have to go on.