Starting at noon, airplane A flies due north at 400 miles per hour. Starting 1 hour later,

Question:

Starting at noon, airplane A flies due north at 400 miles per hour. Starting 1 hour later, airplane B flies due east at 300 miles per hour. Neglecting the curvature of the Earth and assuming that they fly at the same altitude, find a formula for D(t), the distance between the two airplanes t hours after noon.