Exercise 4.7.11

Use greedy inclusion to find the minimum spanning tree:

• The shortest edge is between $(0,0)$ and $(1,0)$, add it to the tree
• The second shortest edge is between $(1,0),(3,0)$, add it to the tree
• The next one is from $(0,4)$ to $(0,0)$
• The last one is from $(0,8)$ to $(0,4)$

The whole tree connects from $(8,0)\to (4,0)\to (0,0)\to (1,0)\to (3,0)$