10. The wave heights h in the open sea depend on the speed v of the wind and the length of time that the wind has been blowing at that speed. Values of the function h = f(v, t) are recorded in feet in the following table. Duration (hours 5 10 15 20 30 40 50 U 10 2 2 2 2 2 2 2 15 A A 5 5 5 5 5 20 5 7 8 Wind speed (knots) 30 16 7 18 19 19 40 14 21 25 28 31 33 33 50 36 40 45 48 50 60 24 37 17 54 67 60 a) What are the meanings of the partial derivatives Oh/av and Oh/at ? b) Estimate the values of fo(40,15) and ft(40,15). What are the practical interpretations of these values? c) What appears to be the value of the following limit? lim t->co ot