总面积： = 50
三角形各边长：
A = 4.4721359549995787
B = 4.12310562561766
C = 3.6055512754639887
此题来自：
http://87.230.22.228/doc/tutorial.pdf
第一百页～一百零一页。
还有图：Fig. 9.6
_(a) _(a) _(a)
===================原题：============================
Consider the following problem:
George is contemplating buying a farm which is a very strange shape, comprising a large triangular lake with a square field on each side. The area of the lake is exactly seven acres, and the area of each field is an exact whole number of acres. Given that information, what is the smallest possible total area of the three fields?
