This keyboarded and encoded edition of the work described above is co-owned by the institutions providing financial support to the Early English Books Online Text Creation Partnership. Searching, reading, printing, or downloading EEBO-TCP texts is reserved for the authorized users of these project partner institutions. Permission must be granted for subsequent distribution, in print or electronically, of this text, in whole or in part. Please contact project staff at eebotcp-info@umich.edu for further further information or permissions.
AN equilater Triangle is that, which hath all his three sides equall; for I neede not stand to define what a Triangle is, seeing it is so well knowne to be a figure made of three lines, either Right or Sphericall, but
here I speak of Right lined Triangles. Now to finde the length of the perpendicular, which is a line falling from the opposite angle to the base, making Right Angles therewith; lay the threed upon the side of the Quadrat, and rectifie the bead to the length of one of the sides; then opening the threed, untill the bead fall upon the right parallel of halfe the base; so shall it shew the con∣trary parallel of the perpendicular.
Let the Triangle ABC, be given, wherein it is re∣quired to since the length of the perpendicular AD: First, lay the threed upon the side of the Quadrat, and rectifie the bead to 8 the length of the side AB, or AC; then open the threed, untill the bead falleth upon the Right parallel of 4, the one halfe of the base BC, which is BD, or CD; so shall the bead cut the contrary pa∣rallel of 6 9/10 which is the length of the perpendicular AD, which was required.
Thus may you likewise finde the perpendicular of an Isoscheles Triangle, which is a Triangle of two equall sides; for, first placing the bead to one of the sides, then
opening the threed untill the bead fall on the Right paral∣lel of one halfe of the base; so shall it shew the contrary parallel of the perpendicular.