Smart, Edward Howard · London : Macmillian and Co. · leaf 167
those at P and D,the parallelogram CDTP is the projection of the square a//jA We have therefore area of parallelogram CDTP = c/;^ x cos 9 = constant for any pair of conjugate diameters CP, CD. If p be the length of the perpendicular from C on the tangentat P, we have therefore area of CDTP =j;.CD =… … Fig. 74. 140 PROJECTIVE GEOMETRY Since in the ellipse - = —^j if NP meet the auxiliary • 1 • ^ /-n- »K AN.NA AC^ -^ circle in Q (Fig. 74), QN^ = AN . NA, PN _BC QN~AC and it follows that Accwdingly the ellipse may he obtained by reducing all (xrdinates of the auxiliary circle in the ratio -. a Ex.…
Geometry, Projective
Internet Archive · California Digital Library · Public Domain Mark 1.0. Free to use for anything.
