To make a square quadrate of any righte lyne appoincted.
First make a plumbe line vnto your line appointed, whiche shall
light at one of the endes of it, accordyng to the fifth
conclusion, and let it be of like length as your first line is,
then open your compasse to the iuste length of one of them, and
sette one foote of the compasse in the ende of the one line, and
with the other foote draw an arche line, there as you thinke
that the fowerth corner shall be, after that set the one foote
of the same compasse vnsturred, in the eande of the other line,
and drawe an other arche line crosse the first archeline, and
the poincte that they do crosse in, is the pricke of the fourth
corner of the square quadrate which you seke for, therfore draw
a line from that pricke to the eande of eche line, and you shall
therby haue made a square quadrate.
_Example._
[Illustration]
A.B. is the line proposed, of whiche I shall make a square
quadrate, therefore firste I make a plumbe line vnto it, whiche
shall lighte in A, and that plumb line is A.C, then open I my
compasse as wide as the length of A.B, or A.C, (for they must be
bothe equall) and I set the one foote of thend in C, and with
the other I make an arche line nigh vnto D, afterward I set the
compas again with one foote in B, and with the other foote I
make an arche line crosse the first arche line in D, and from
the prick of their crossyng I draw .ij. lines, one to B, and an
other to C, and so haue I made the square quadrate that I
entended.