Achaemenid engineers had been using PI number in
geometry 2500 years ago. They used this mathematical concept in
building the conical stone structures and columns in Persepolis.
Pi representing the ratio of the circumference of a circle to its
diameter is one of the most important discoveries in geometry.
Mathematicians today still don't know the exact date when this
number was first used. Many people believe that the Egyptians have
been the discoverers of this number, and some consider the Greek
as its discoverer. But new studies show that the Achaemenids were
also familiar with this concept.
"New research on Persepolis structures and especially its
columns and conical shapes show that the Achaemenids 2500 years
ago used the assistance of mathematicians who had solved the
mystery of pi for building conical shapes", Abdol-azim Shah-karami,
a geophysics expert responsible for studying the engineering of
Persepolis structure, told CHN.
The precision in building the Persepolis circular columns shows
that these mathematicians had calculated pi to several decimal
places. "The Achaemenid engineers could determine the exact
conic section of each circular column, and in order to do this,
they had to calculate pi to several decimal places. This helped
them calculate the height of columns and the pressure on them, and
distribute the tension on the conic section of each column",
According to historical records, the first person to be able to
exactly calculate pi was the Muslim scientist, Ghiasoddin Mohammad
Kashani. He computed pi to several decimal places, and scientists
like Pascal followed him with more precise calculations. Referring
to conic sections in different parts of Persepolis, Shah-karami
said it would have been impossible to measure the area and
circumference of these circular and oval structures without
Darius the Great, the Achaemenid Emperor, founded Persepolis, near
Shiraz in Fars province, in 521 BCE, and the planning and building
of many structures in Persepolis including palaces, residences,
water canals, and so on.