19.Find dy and Ay for f(x) = x2 5 as x changes from 3 to 3.01. (Ans: dy = 0.06,Ay = 0.0601) 20. Find % arctan (5%) using implicit differentiation. 21A landowner needs to enclose a field with a rectangular fence. They wish to use 500 m of fencing and a building on one side so no fencing in needed there. Determine the dimensions that will enclose the largest area. (Ans: 125 m by 250 m)