[问答题]
Farmer Thomas wants to build a sheep
je) t ( ,f:+9sw1rmjqplbf5 qegsxn9.3 q,fx xfarming field in the shape of a rectan
j-*l5 p jjny/oia vc31gle with semicircles of radius r on two sides, as shown on the d
i5njy o/1 3j*cl-apvj iagram. He has decided to use in total 350 metres of wooden fencing.
1. 1. Find an expression for the area of the farming field in terms of r .
2. Find the width of the farming field when the area is a maximum.
2. Show that in this case the length of the rectangle is equal to zero and the farming field is the circle of radius 175 $\pi^{-1}$ metres.
