Smart, Edward Howard · London : Macmillian and Co. · leaf 262
. A … Taking the ranges determined by these pencils on BC, BCrespectively, we have { BDEC} = {DBCE}. Hence, if a conic touch AB, AC, AB, AC and one of the twoBC, BC (see §6 (b), Chap. XIV.), it must, by §7 (b) of thatchapter, touch the other. To prove the converse, we have simpl}^ to reverse the stepsof…
Geometry, Projective
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