Analytic geometry, for technical schools and colleges (1897)
Lambert, Preston Albert, 1862-1925 · New York, Macmillan · leaf 169
d is called the class ofthe curve. Art. 79. — Cross-ratio of a Pencil of Four Eays Let a pencil of four rays, P=0, Q = 0, P-|-X,Q = 0, P-fA,Q = 0, be cut by any transversal in the four points A, B, C, D. j^ isthe common altitude of the triangles whose common vertexis 0, and whose bases lie in the… … 154 ANALYTIC GEOMETRY called the cross-ratio of the pencil of four rays. It is evident that central projection doesnot alter the cross-ratio offour points in a straightPA \ ^^ line. Writing the equationP-|-XQ = 0 in the com-Q=0 plete formu^x + i\y + 1 FiG 138. and this in the form the factor…
Geometry, Analytic
Internet Archive · California Digital Library · Public Domain Mark 1.0. Free to use for anything.
