Problem 38: Analogy between two problems

I have been reading 'Why Don't Students Like School?' by Daniel Willingham, and I came across with these problems:

Problem 1:
Suppose you are a doctor faced with a patient who has a malignant tumor in his stomach. It is impossible to operate on the patient, but unless the tumor is destroyed, the patient will die.There is a kind of ray that can be used to destroy the tumor. If the rays reach the tumor all at once at a sufficiently high intensity, the tumor will be destroyed. Unfortunately, at this intensity, the healthy tissue the rays pass through on the way to the tumor will also be destroyed. At lower intensities, the rays are harmless to healthy tissue, but they will not affect the tumor either. What type of procedure might be used to destroy the tumor with the rays and at the same time avoid destroying the healthy tissue?*

Problem 2:
A dictator ruled a small country from a fortress.The fortress was situated in the middle of the country, and many roads radiated outward from it, like spokes on a wheel. A great general vowed to capture the fortress and free the country of the dictator.The general knew that if his entire army could attack the fortress at once, it could be captured. But a spy reported that the dictator had planted mines on each of the roads.The mines were set so that small bodies of men could pass over them safely because the dictator needed to be able to move troops and workers about; however, any large force would detonate the mines. Not only would this activity blow up the road, but the dictator would destroy many villages in retaliation. How could the general attack the fortress?**


The two questions describe similar phenomena, but the people who solved the first one or given the solution to the first one, mostly cannot answer the second one. Or they do not see the same relationship between the two triangles. Can you see?

*Willingham, Daniel T. Why Don't Students Like School?: A Cognitive Scientist Answers Questions About How the Mind Works and What It Means for the Classroom (p. 98). Wiley. Kindle Edition. 

**Willingham, Daniel T. Why Don't Students Like School?: A Cognitive Scientist Answers Questions About How the Mind Works and What It Means for the Classroom (pp. 98-99). Wiley. Kindle Edition.