# Scholia in opticorum recensionem Theonis (scholia vetera) 57

Scholia in Euclidem, Scholia in opticorum recensionem Theonis (scholia vetera), Section 57. Ancient Greek.

Canonical: https://interlinea.aeterna-institute.org/library/greek/scholia-in-euclidem/scholia-in-opticorum-recensionem-theonis-scholia-vetera/57

57. Ὀρθὴ ἄν εἴη p. 20Ο, ἐπεὶ γὰρ ἴση ἐστὶν ἡ Κ∠Β γωνία τῇ ΚΒ∠, ἡ δὲ ΚΖΒ τῇ ΖΒΚ, δύο ἄρα αἱ Β∠Κ, ∠ΖΒ δύο ταῖς ΖΒΚ, ΚΒ∠ ἴσαι εἰσίν. ὥστε αἱ τέσσαρες αἱ ΒΖΚ, Ζ∠Β, ∠ΒΚ, ΚΒΖ δύο τῶν ∠ΒΚ, ΚΒΖ, τουτέστι τῆς ∠ΒΖ, διπλασίονές εἰσιν. ἀλλὰ αἱ τέσσαρες δύο ὀρθαῖς ἴσαι εἰσίν· ἐν τῷ τριγώνῳ γάρ εἰσι τῷ ∠ΖΒ. ὥστε ἡ ∠ΒΖ γωνία ὀρθή ἐστιν.

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Scholia in Euclidem, Scholia in opticorum recensionem Theonis (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.tlg004.local001/.