To cutte of from a circle appointed, a portion containyng an
angle equall to a right lyned angle assigned.
When the angle and the circle are assigned, first draw a touch
line vnto that circle, and then drawe an other line from the
pricke of the touchyng to one side of the circle, so that
thereby those two lynes do make an angle equall to the angle
assigned. Then saie I that the portion of the circle of the
contrarie side to the angle drawen, is the parte that you seke
for.
_Example._
[Illustration]
A. is the angle appointed, and D.E.F. is the circle assigned,
from which I must cut away a portion that doth contain an angle
equall to this angle A. Therfore first I do draw a touche line
to the circle assigned, and that touch line is B.C, the very
pricke of the touche is D, from whiche D. I drawe a lyne D.E, so
that the angle made of those two lines be equall to the angle
appointed. Then say I, that the arch of the circle D.F.E, is the
arche that I seke after. For if I doo deuide that arche in the
middle (as here is done in F.) and so draw thence two lines, one
to D, and the other to E, then will the angle F, be equall to
the angle assigned.