A higher resolution image, from a slightly different viewpoint
The roof of the Persian Throne Room of the Taq-i-Kisra, now in Iraq, is the best surviving example of an ancient large span structure built to a catenary profile, the shape that will minimise bending moments in a structure of uniform thickness, standing under its own weight.
The red line added to the photograph is a catenary, and the blue line a parabola with the same span at first floor level. The plot suggests that the roof shape from first floor level does indeed approximate a catenary, although the low resolution photograph and irregular outline of the end face of the structure make it difficult to be certain.
Newton Excel Bach, not (just) an Excel Blog 
Looks like a cantenary on the inside and a parabola on the outter surface. Looks a bit like a bit of thickening in the structure at the base of the arch
LikeLike
Pingback: Elegant proofs 4 – The optimum shape of an arch « Newton Excel Bach, not (just) an Excel Blog
Hey
You’re not likely to check this anytime soon, but if you do, could you please email me the link of the second picture untouched, or it itself
its for a school add maths project
LikeLike
Hi Fisher
This is the link I used:
Hope your project goes well.
If you are working on arches you might be interested in this post as well:
https://newtonexcelbach.wordpress.com/2009/06/16/elegant-proofs-4-the-optimum-shape-of-an-arch/
LikeLike
Thanks a lot, it’ll help a lot
LikeLike
Hey,
Just a minor correction, Taq-i-Kisra is in Iraq not Iran although it was named after a Persian emperor.
http://en.wikipedia.org/wiki/Taq-i_Kisra
LikeLike
Thanks Sam. I have corrected the text.
LikeLike