Hi all I am new to the forum. I'm a designer for theatre and I'm having some trouble figuring out a scenic piece I want to build. The piece is essentially an obelisk with a triangular base. The three sides of the solid are trapezoids with 4' wide base, 2'-10" wide top and an overall height of 14' (dimensions shown in the image). The base is an equilateral triangle with 4' sides and the top is an equilateral triangle with 2'-10" sides. Each of the sides must slope back slightly in order for their edges to meet. So the two questions are: 1) What is that angle? (shown as angel n) 2) What is the overall height of the solid? Thanks so much for your help! ~M.