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Published 1997 Revised 2011
This is the second of the two articles on rightangled triangles whose edge lengths are whole numbers. We suppose that the lengths of the two sides of a rightangled triangles are $a$ and $b$, and that the hypotenuse has length $c$ so that, by Pythagoras' Theorem,$$a^2 + b^2 = c^2$$.
In the first article we discussed the possibility of enlarging or shrinking a rightangled triangle to get another rightangled triangle whose sides also have lengths that are whole numbers, and we claimed there that apart from a possible scaling of the triangle, every such rightangled triangle has edge lengths of the form
$a=2pq \; \; \;$  $b=p^2q^2 \; \; \;$ 
$c=p^2+q^2$
