[Illustration]
The answer given in all the old books is that shown in Fig. 1, where the
curved wall shuts out the cottages from access to the lake. But in
seeking the direction for the "shortest possible" wall most readers
to-day, remembering that the shortest distance between two points is a
straight line, will adopt the method shown in Fig. 2. This is certainly
an improvement, yet the correct answer is really that indicated in Fig.
3. A measurement of the lines will show that there is a considerable
saving of length in this wall.