Smart, Edward Howard · London : Macmillian and Co. · leaf 196
ocal distances of the point. Let SY, SY (Figs. 87a and b), SZ, SZ be the perpendicularsfrom the foci on the tangents from T. Then SY.SY = BC- = SZ .SZ (§3 (/>)). . SY _ SZSZ~STand angle YSZ = angle YSZ, each being equal to (in Fig. 87/>),or supplementary to (in Fig. 87a), the angle YTZ. ..… … aiG. 67a. cyclic, angle SYZ = angle STZ in Fig. 87b, but supplement ofangle STZ in Fig. 87a. .. angle STY = angle STZ in both cases.
Geometry, Projective
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