I'm not sure why I'm having trouble with these... can someone give me a start or some help through them?

A man walks a straight path at a speed of 4 ft/sec. A search light is located on the ground 20 ft rom the path and is kept focused on the man. At what rate is the searchlight rotating when the man is 15 ft from the point on the path closest to the searchlight?

and

Two people start from the same point. One walks north at 3 mph and the other northeast (45 degrees exactly) at 2 mph. How fast is the distance between them changing after 15 minutes? (Hint: use the law of cosines to relate the variables)