This painted bas-relief is from the east wall of
the chapel of the tomb built for Petosiris
and his family around 300 BC.
Here is the drawing of a geometrical model
for the bas-relief, showing the golden
triangle: 1, PHI, SQR ROOT(PHI^2 + 1)
clearly represented in the bas-relief.
The analysis by Lucy Lamy is presented in
Robert Lawlor, Sacred Geometry, pp. 54-55.