Below is a transcription of a {ctional} student's solution to a related rates problem. There are several aws in the solution: at least three procedural errors, and room for improvement in the presentation. For each flaw that you nd, say what the mistake is, and how to x it. Problem: Two cars leave from an intersection at the same time. Car A travels south at 80 kmlh, while car B travels east at 60 kmlh. At what rate is the distance between the cars increasing one hour later? Solution: (my beautiful ASCII triangle diagram isn't one of the flaws) fz ." | l y I 1' I II From the diagram, :2 + y2 = :2. So do: {1 dz :2+y2 y _ 2 _ 2: . alt {It dt Car A is travelling south, and that's negative, so % : 60. Car B is travelling east, and that's positive, so % = 89. After one hour, car A has gone 60 km and car B has gone 80 km, and 2: =1/(00)2 + [00)2 = 00+ 30 = 140 Plugging in: 2 2d: 00 (00] + 802(80] = 140 E d 200000 2' = 151th E _ 19000