A Conversation for Calculating the Volume and Surface Area of Various Solid Objects
Pyramid's surface
Amator Started conversation Oct 31, 2000
'...the pyramid can be broken down into a square and four identical triangles' - then the formula should say '0.5lw' four times, not three?
The torus calculations surprised me a bit. I never had the need for them and somehow never thought of finding out... Elegant.
Amator
Pyramid's surface
Amator Posted Oct 31, 2000
Well, and 4 times 0.5lw is 2lw (in the second formula)...
You also forgot to add the base (pr^2) for the simple cone's surface area 
The entry looks much better now.
Amator
Pyramid's surface
Peter aka Krans Posted Nov 1, 2000
Okay... fixed it... thanks again for pointing it out...
Pyramid's surface
Amator Posted Nov 2, 2000
Are you sure that the simple cone's surface area is pr^2l ? This looks more like area of a cylinder to me. Your previous version showed prl, and that was correct for the "side" surface area. What was left out was the circular base (pr^2), which should be added to get the correct (I think) formula: S = pr^2 + prl or S = pr(r+l).
Or maybe I am completely wrong? This may be the case, as I did not check it out in books and I haven't done this kind of maths for a long time...
Amator
Pyramid's surface
Peter aka Krans Posted Nov 2, 2000
You're right - the correct equations is S = prl + pr^2
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Pyramid's surface
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