Ibn-al-Haitam, al-Hasan Ibn-al-Hasan; Witelo; Risner, Friedrich, Opticae thesavrvs Alhazeni Arabis libri septem, nunc primùm editi. Eivsdem liber De Crepvscvlis & Nubium ascensionibus. Item Vitellonis Thuvringopoloni Libri X. Omnes instaurati, figuris illustrati & aucti, adiectis etiam in Alhazenum commentarijs, a Federico Risnero, 1572
<head xml:id="echoid-head355" xml:space="preserve" style="it">52. Si à puncto in communi ſectione ſuperficierum, reflexionis & ſpeculi conici conuexi dato, re
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flexio fiat: poſſunt uiſ{us} & uiſibile ſic collocari, ut ab eodem puncto, tanquam puncto circuli ba-
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ſi paralleli ad uiſum reflexio fiat. 32 p 7.</head>
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<s xml:id="echoid-s9940" xml:space="preserve">REſtat in his ſpeculis declarare:</s>
<s xml:id="echoid-s9941" xml:space="preserve"> quòd ab uno ſolo puncto eius fiat reflexio:</s>
<s xml:id="echoid-s9942" xml:space="preserve"> quod ſic patebit.</s>
<s xml:id="echoid-s9943" xml:space="preserve">
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Sit uiſus a:</s>
<s xml:id="echoid-s9944" xml:space="preserve"> b punctũ uiſum:</s>
<s xml:id="echoid-s9945" xml:space="preserve"> g punctũ reflexionis:</s>
<s xml:id="echoid-s9946" xml:space="preserve"> & ducatur ſuper punctũ g ſuperficies æqui
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diſtãs baſi:</s>
<s xml:id="echoid-s9947" xml:space="preserve"> [ductis nimirũ duabus perpẽdicularibus ſuper axem ſe interſecãtibus:</s>
<s xml:id="echoid-s9948" xml:space="preserve"> una qui-
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dẽ à reflexionis puncto per 12 p 1:</s>
<s xml:id="echoid-s9949" xml:space="preserve"> altera uerò ab axis puncto, in quod illa cadit, per 11 p 1.</s>
<s xml:id="echoid-s9950" xml:space="preserve"> Sic enim
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axis, qui per 18 d 11 perpendicularis eſt baſi:</s>
<s xml:id="echoid-s9951" xml:space="preserve"> erit per 4 p 11 perpendicularis plano ductarũ perpendi
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culariũ.</s>
<s xml:id="echoid-s9952" xml:space="preserve"> Quare per 14 p 11 baſis & hoc planũ erunt parallela] quę quidẽ ſecabit pyramidẽ ſuper cir-