A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . THE COMPLETE QUADRILATERAL. A Complete Quadrilateral is formed by Fig. 412. drawing any four straight lines, so that eachof them shall cut each of the other three, soas to give six different points of is so called because in the figure thusformed are found three quadrilaterals ; viz.,m Fig. 412, ABCD, a common convex quadri-
A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . THE COMPLETE QUADRILATERAL. A Complete Quadrilateral is formed by Fig. 412. drawing any four straight lines, so that eachof them shall cut each of the other three, soas to give six different points of is so called because in the figure thusformed are found three quadrilaterals ; viz.,m Fig. 412, ABCD, a common convex quadri-lateral ; EAFC, a uni-eoncave quadrilateral;and EBAFD, a bi-eoncave quadrilateral, com-posed of two opposite triangles. The complete quadrilateral, AEBCDF, hasthree diagonals; viz., two interior, AC, BD;and one exterior, EF. Theorem VIII.—Li every complete quadrilateral the middle points of its threediagonals lie in the same straight line. AEBCDF is the quadrilateral, and LMN the middle points of its three diago-nals. From A and D draw parallels to BC, and from B and C draw parallels to. 392 THE COMPLETE QUADRILATERAL. [app. b. Fig. 413.
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectsurveying, bookyear18
