I believe this problem needs to be solved using implicit differentiation, but i am not sure how to set the problem up.. any help is greatly appreciated.

People standing on a cliff watch a sailboat move away from the base of the cliff. The boat is traveling at 3 m/s and the cliff is 150 meters tall. Not taking into account the earth’s curvature, how fast is the distance between the people and the boat increasing when the boat is 200 meters from the base of the cliff?