Today:
The proof that the square root of 2 is irrational is based on contradiction: we assume that it is rational, and then discover that it leads to an impossibility. We could use the same idea to show that the square root of 5 is irrational.
And [Solomon] made a molten sea, ten cubits from the one brim to the other [diameter = 10]: [it was] round all about [a circle], and his height [was] five cubits: and a line of thirty cubits did compass it round about [circumference = 30].
Pi = circumference/diameter = 3!?! Even so, that's better than the Indiana legislature did, a few thousand years later, as our authors note in the text (p. 119).
(See also http://www.yfiles.com/pi.html for the Biblical calculation of pi.)
Archimedes did a lot better, born in about 287 BC in Syracuse, Sicily -- check out this applet that shows how he did it!
Next time: Golden Rectangles....