PAL

Ptolemaeus Arabus et Latinus

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πρὸς ὀρθὰς γωνίας ‘at right angles’

Greek

References: Alm. Heiberg: I.7, 22:3
Translated into:
Arabic: على زوايا قائمة [Alm. MS Tunis: ]
Modern translations:
English: at right angles [Alm. Toomer: 43]