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A history of Greek mathematics - Wilbourhall.org

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;<br />

ARISTARCHUS OF SAMOS<br />

9<br />

I. Now, by Hypothesis 4, /.ABC = 87°,<br />

so that Z HBE = Z 5ZIC = 3°<br />

therefore Z.GBE:lHBE=iR: 3 \R<br />

= 15:2,<br />

so that GE:HE[ = tan ££# : tan #£#] > Z QBE : Z #£#<br />

> 15 :2. (1)<br />

The ratio which has to be proved > 18:1 is AB:BC or<br />

FE:EH.<br />

Now<br />

FG:GE=FB:BE,<br />

whence FG 2 : GE = 2 FB 2 : BE<br />

and FG:GE = V2:1<br />

> 7:5<br />

2 =2:1,<br />

(this is the approximation to V2 mentioned by Plato and<br />

known to the Pythagoreans).

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