# Scholia in Euclidis optica (scholia vetera) 44

Scholia in Euclidem, Scholia in Euclidis optica (scholia vetera), Section 44. Ancient Greek.

Canonical: https://interlinea.aeterna-institute.org/library/greek/scholia-in-euclidem/scholia-in-euclidis-optica-scholia-vetera/44

44. Ὀρθαὶ ἄρα αἱ πρὸς τῷ Κ p. 38, διὰ τί ὀρθαὶ αἱ πρὸς τῷ Κ; ἐπεὶ κύκλου τοῦ ΑΓΒ∠ ἐφ ἀπτηταί τις εὐθεῖα ἡ HΘ, ἀπὸ δὲ τοῦ κέντρου ἐπὶ τὴν ἐπαφὴν ἐπεζεύχθη εὐθεῖα ἡ ΒΑ, ἡ ἐπιζευχθεῖσα ἄρα κάθετος ἔσται ἐπὶ τὴν ἐφαπτομένην· ὀρθὴ ἄρα ἡ ὑπὸ ΒΑΗ. ἐπεὶ δὲ εἰς παραλλήλους τὰς ΗΘ, Γ∠ εὐθεῖα ἐνέπεσεν ἡ ΑΒ, ἡ ἐκτὸς γωνία ἡ ὑπὸ ΒΚΓ ἴση ἐστὶ τῇ ἐντὸς καὶ ἀπεναντίον τῇ ὑπὸ ΒΑΗ ὀρθὴ δὲ ἡ ὑπὸ ΒΑΗ καὶ ἡ ὑπὸ ΒΚΓ. ὀρθαὶ ἄρα αἱ πρὸς τὸ Κ.

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Scholia in Euclidem, Scholia in Euclidis optica (scholia vetera), ed. Johan Ludvig Heiberg, H. Menge. Text: The Greek Library, from the Perseus Digital Library and other open sources, CC BY-SA 4.0. Changes: apostrophes normalised and the text divided into reading sections by Interlinea.
License: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/). Source: https://thegreeklibrary.pages.lisn.upsaclay.fr/works/tlg5022.tlg003.local001/.