NavList:

Dear Sean,

Thanks for your so (and even too) kind and nice comments.

Spending over 10 years as an aircraft carrier fighter pilot has helped me a lot into 3D thinking, and this sometimes remains quite useful even nowadays when flying A340's . Before starting flight training I had to endure a solid Math training for 6 years including a course on "Geométrie descriptive" during 2 years (not easy at all then). When I spotted that flat Pyramid on paper I was immediately back into same familiar albeit quite remote aea.

3D geometry is no longer taught in European high schools, only in universities, and this is certainly a pity because 3D thinking is a real plus even in day-to-day life. And it is also an excellent brain exercise because it requires some kind of parallel thinking.

Nonetheless, I found this one a bit disorienting. Only when I had my pyramid in hand, could I then fully confirm my immediate suspiscion. So my analysis in post g30505 is not so impressive: it all flowed from harsh challenging questions - during last night sleep - about my small paper Pyramid made yesterady evening.

And Yes ! Given post g30486 I am now including Hanno into my credit list. Thanks to both of you then, I could revert to a pair of scissors and some glue: back into childhood !

Have a Great day !

Kermit