To make a siseangle of equall sides, and equall angles, in
any circle assigned.
Yf the centre of the circle be not knowen, then seeke oute the
centre according to the doctrine of the sixtenth conclusion. And
with your compas take the quantitee of the semidiameter iustly.
And then sette one foote in one pricke of the circumference of
the circle, and with the other make a marke in the circumference
also towarde both sides. Then sette one foote of the compas
stedily in eche of those new prickes, and point out two other
prickes. And if you haue done well, you shal perceaue that there
will be but euen sixe such diuisions in the circumference.
Whereby it dothe well appeare, that the side of anye sisangle
made in a circle, is equalle to the semidiameter of the same
circle.
_Example._
[Illustration]
The circle is B.C.D.E.F.G, whose centre I finde to bee A.
Therefore I sette one foote of the compas in A, and do extend the
other foote to B, thereby takinge the semidiameter. Then sette I
one foote of the compas vnremoued in B, and marke with the other
foote on eche side C. and G. Then from C. I marke D, and from D,
E: from E. marke I F. And then haue I but one space iuste vnto
G. and so haue I made a iuste siseangle of equall sides and
equall angles, in a circle appointed.