Barrow, Isaac
,
Lectiones opticae & geometricae : in quibus phaenomenon opticorum genuinae rationes investigantur, ac exponuntur: et generalia curvarum linearum symptomata declarantur
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niam jam eſt KF &</
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<
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<
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reſtare FE &</
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<
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<
s
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">Ità quidem ab una rectæ BQ parte recta BR duci poteſt, quæ mi-
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nores ipſis MN intercipiat; </
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<
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"> poteſt autem ab altera parte recta quoque duci, quæ minores intercipiat ipſis F E; </
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<
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Propoſitum.</
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<
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xml:space
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guli rectilinei BFC, cujus latera ſecet recta DBC; </
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ducta ſit recta EG; </
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">poteſt ab E recta duci (ceu EH) talis, ut à
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puncto D projectâ utcunque rectâ DK ſit in hac à rectis EG, EH in-
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tercepta minor à rectis FC, FB interceptâ.</
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<
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<
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ubi punctum E puncto D vicinius eſt, (ob ſimilitudinem triangulorum
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ENM, FKI) manifeſtum eſt fore MN &</
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xml:space
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tem ab E duci recta (puta EH) talis, ut interceptæ PO minores ſint
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interceptis MN; </
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<
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ipſi CB; </
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<
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DF. </
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MN. </
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<
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ceu E H, ſic ut ab EG, EH interceptæ OP minores ſint interceptis
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QN. </
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qualis curvæ B A; </
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ctatur recta KO; </
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<
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eſt BK + KO &</
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punctis K, L, connexâque rectâ KL; </
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_dæis_) adeóque KL + LO &</
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