draw a corde,
other a stringline. And then accordyng as you dyd in one arche
in the .xvi. conclusion, so doe in bothe those arches here, that
is to saie, deuide the arche in the middle, and also the corde,
and drawe then a line by those two deuisions, so then are you
sure that that line goeth by the centre. Afterward do lykewaies
with the other arche and his corde, and where those .ij. lines
do crosse, there is the centre, that you seke for.

_Example._

[Illustration]

The arche of the circle is A.B.C, vnto whiche I must seke a
centre, therfore firste I do deuide it into .ij. partes, the one
of them is A.B, and the other is B.C. Then doe I cut euery arche
in the middle, so is E. the middle of A.B, and G. is the middle
of B.C. Likewaies, I take the middle of their cordes, whiche I
mark with F. and H, settyng F. by E, and H. by G. Then drawe I a
line from E. to F, and from G. to H, and they do crosse in D,
wherefore saie I, that D. is the centre, that I seke for.

THE XXVII. CONCLVSION.

To drawe a circle within a triangle appoincted.

For this conclusion and all other lyke, you muste vnderstande,
that when one figure is named to be within an other, that it is
not other waies to be vnderstande, but that eyther euery syde of
the inner figure dooeth touche euerie corner of the other, other
els euery corner of the one dooeth touche euerie side of the
other. So I call that triangle drawen in a circle, whose corners
do touche the circumference of the circle. And that circle is
contained in a triangle, whose circumference doeth touche
iustely euery side of the triangle, and yet dooeth not crosse
ouer any side of it. And so that quadrate is called properly to
be drawen in a circle, when all his fower angles doeth touche
the edge of the circle, And that circle is drawen in a quadrate,
whose circumference doeth touche euery side of the quadrate, and
lykewaies of other figures.

_Examples are these. A.B.C.D.E.F._

[Illustration:
A. is a circle in a triangle.
B. a triangle in a circle.
C. a quadrate in a circle.
D. a circle in a quadrate.]

In these .ij. last figures E. and F, the circle is not named to
be drawen in a triangle, because it doth not touche the sides of
the triangle, neither is the triangle counted to be drawen in the
circle, because one of his corners doth not touche the
circumference of the circle, yet (as you see) the circle is
within the triangle, and the triangle within th