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-head339" xml:space="preserve" style="it">36. Duob{us} punctis extra circuli peripheriam, uel uno extra, reliquo intra datis: inuenire in
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peripheria punctum, in quo recta linea ipſam tangẽs, bif ariam ſecet angulum comprehenſum