Book I

on the measurement of areas is specially interesting for (1) its statement of the formula used by Heron for finding approximations to surds, (2) the elegant geometrical proof of the formula for the area of a triangle Δ {D} = √{_s (s-a) (s-b) (s-c)}, a formula now known to be due to Archimedes, (3) an allusion to limits to the value of π {p} found by Archimedes and more exact than the 3-1/7 and 3-10/71 obtained in the _Measurement of a Circle_.