Subject: compound angles

I am presently trying to build a pyramid. I can understand that the base has 90 degree angles on the first plane which is the outline of the square that makes up the floor.

As close as I can figure the slope of each wall face is 35 degrees or 35.7 to be exact if I am correct by using 360 as the total of the three interior angles.Now , I run into a compound angle where the corners meet what would be the angle created by the two 35 degree angles that would allow for the 90 degree edge to continue.

Because I'm working in three dimensions I also need to be sure that my math would be correct when I substract 35 from 90 to aquire the angle of the narrow edge as to allow for a 90 degree surface to be present allow for another level to be added with only the base line being shortened. I hope you can understand what it is that I'm asking assistance with.I would greatly appericate your help.


Mr.Francis X. Hines Jr.


I don't understand the question. Perhaps the best idea would be to build a scale model out of cardboard. The sides would be 4 identical isosceles triangles whose base b is equal to the desired base of your pyramid, while the height of the triangle, say s, would be the slant height of the finished pyramid. The actual height of the pyramid will then be SQRT[s2 - (b/2)2]. The angle between the sides of the pyramid are hard to measure and irrelevant to the builder. (The angle between two blocks at a corner would be 90 degrees because the cross section at each level is a horizontal square -- it would be just like the corner of a rectangular building)

I hope this helps,
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