# Dioptra 11

Hero of Alexandria, Dioptra, Chapter 11. Ancient Greek.

Canonical: https://interlinea.aeterna-institute.org/library/greek/hero-of-alexandria/dioptra/11

ια. Τῇ δοθείσῃ εὐθείᾳ πρὸς ὀρθὰς ἀγαγεῖν ἀπὸ τοῦ πέρατος αὐτῆς, μὴ προσεγγίσαντα μήτε τῇ εὐθείᾳ μήτε τῷ πέρατι. ἔστω ἡ μὲν δοθεῖσα εὐθεῖα ἡ ἐπὶ τὰ Α, Β σημεῖα ἐπιζευγνυμένη· ἀφʼ οὗ δὲ δεῖ τὴν πρὸς ὀρθὰς ἀγομένην εὑρεῖν, ἔστω τὸ Α. εὑρήσθω ἡ θέσις τῆς ΑΒ ἐν τοῖς πρὸς ἡμᾶς τόποις, ὡς ἐμάθομεν· καὶ ἔστω ἡ Γ∠ εὐθεῖα. παράγω οὖν τὴν διόπτραν ἐπὶ τῆς Γ∠ εὐθείας διατηρῶν τὸν κανόνα ἀεὶ ἀποβλέποντα σημείῳ τινὶ τῶν ἐπὶ τῆς Γ∠, ἄχρις ἂν ἐπιστραφεὶς ἐπὶ τὴν πρὸς ὀρθὰς θέσιν ἴδῃ τὸ Α σημεῖον. τετυχέτω οὖν ἡ διόπτρα πρὸς τὸ Ε σημεῖον· ἔσται δὴ πρὸς ὀρθὰς εἶναι τὴν ΑΕ.

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Hero of Alexandria, Dioptra, ed. Hermann Schöne. 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/tlg0559.tlg007.local001/.