RandallB said:
In no way can the word discribe something that has an area.
Think of it as though it were an animation. Going from diagram 1 to diagram 2, the "hypotenuse" of the large triangle goes from being concave to convex. The area that is contained within the change of the hypotenuse is the same area that's described by the parallelogram. Hence, by viewing the hypotenuse as a discrete, flexible element that changes with 'time' over an area, "hypotenuse" describes the location and the area just as well as "parallelogram" does.
In fact, I might argue that human-understainding-wise, "hypotenuse" might be a better answer, because the hypotenuse of the large triangle is already clearly drawn on each diagram, hence it's already been established and can be examined as a potential answer. The "parallelogram" you reference, however, isn't clearly drawn on the diagram, and as such isn't as immediately clear of a concept.
RandallB said:
Emotional reactions like yours seem way to unproductive to waste time on – maybe I should just ignore them
Why wouldn't you? For that matter, why did you bother making the assesment "Complaints to the contrary are just sour grapes over not figuring out the whole solution on their own"? You're quite intentionally pointing out other people's emotional reactions and branding them as negative, as well as implying their stupidity, more directly by declaring that they lack understanding of the problem. I think it was a waste of your time to point that out, and only served to hurt other people's feelings (probably making them feel defensive), and (as I'm trying to point out) could be entirely inaccurate.
The only reason I'm pointing it out here is to try and get you to realize that the comment (the attitude really) was unnecessary and divisive. I'm making the point in the hopes that you won't do such things in the future. It doesn't help to the understanding of the brain teaser in question, and only serves to make a more hostile environment in the forums.
If you think someone has an incorrect solution, try and either explain why it isn't correct or have them try to explain why it *is* correct. Please don't just assume that they're clueless and treat them as such.
DaveE