Replies

1. 
   PeteBradley | Aug 13, 2006 05:22pm | #1

   I think you're asking: given a regular trapezoid with known height(H) base(B) and top(T) meaurements, find the bottom corner angles. I'm doing the trig as I go along, but I think it would be:

   angle = inverse tangent of H/(B-T)

   For a lampshade it would be pretty easy to lay out and measure also.

   Pete

1. 
   tkumpf | Aug 13, 2006 08:16pm | #2

   Pete,
   I'm not looking for corner angles, but the bevel angles that will run
   along the sides of the 4 trapezoids that will allow them to come
   together to make 4 sided pyramid
   tom

2. 
   QCInspector | Aug 13, 2006 08:21pm | #3

   This online calculator should work.

   http://www.josephfusco.org/Calculators/Advanced_Box_Cutter.html

1. 
   tkumpf | Aug 14, 2006 03:33pm | #5

   QCInspector,
   Thanks so much this is what I needed! What a powerful calculator.
   tom

3. 
   mufti | Aug 14, 2006 02:09pm | #4

             Beware of engineering pocket books! I have spent some interesting time trying to apply a formula to a trapezium because of an error in the definitions of plane figures in my Newnes Engineer's Book,1960 edition.