Examples from Section 14.1
The first is an animation of Figure 11, p. 883 (14.1):
![Level Curves Figure 11](14_1Fig11.gif)
The next is an animation of Figure 17, p. 885. Again, we're showing
level curves.
![Level Curves Figure 17](14_1Fig17.gif)
This is an animation of Figure 19, plots (a) and (b).
![Figure 19](14_1Fig19A.gif)
This is an animation of Figure 19, plots (c) and (d).
![Figure 19](14_1Fig19B.gif)