A history of Greek mathematics - Wilbourhall.org

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524 COMMENTATORS AND BYZANTINES
until 6 = \tt when it is a maximum, the triangle being then
isosceles (Prop. 24).
In Prop. 29 Serenus takes up the third class of sections with
bases parallel to d. If the base of such a section is 2x,
A=xV(r 2 -x 2 +p 2 )
and, as in the case of
maximum value
the right cone, we must have for a real
x 2 = \ (r 2 +2 j2 )>
while x