52
ARCHIMEDES
and Zeuthen) is that the successive solutions in integers of
the equations
x 2 ~3y 2 =l I
- 2 .3y 2 - -23
x“
may have been found in a similar way to those of the
equations ic 2 — 2 y 2 = +1 given by Theon of Smyrna after
the Pythagoreans, The rest of the suggestions amount for the
most part to the use of the method of continued fractions
more or less disguised.
or
Applying the above formula, we easily find
2-±>V3 >2-|,
1>V3 >|.
Next, clearing of fractions, we consider 5 as- an approxi
mation to V3.3 2 or V27, and we have
5 + x^>3v'3>5 + 1 2 T)
whence ft > V 3 > xf •
Clearing of fractions again, and taking 26 as an approxi-
mation to 3.15 2 or V675, we have
26-#2 > 15V3 > 26—^r,
which reduces to
13S1 ./q 265
7 8 0' > V 0 > X5 3-.
Archimedes first takes the case of the circumscribed polygon.
Let CA be the tangent at A to a circular arc with centre 0.
Make the angle AGO equal to one-third of a right angle.
Bisect the angle AGO by OD, the angle AOD by OE, the
angle AO A by GF, and the angle AGF by OG. Produce GA
to AH, making AH equal to AG. The angle GOH is then
equal to the angle FOA which is ^th of a right angle, so
that GH is the side of a circumscribed regular polygon with
96 sides.
GA:AG[= V3 : 1] > 265:153,
GC : CA = 2:1 = 306:153.
(1)
(2)
And
so that
Henc
And
Thert
Nex
from (
of 0A
G A: A
G A: A
Deal
similar
angle
if the
the ar
straigl
96 sidi