[56] 56. Ἴσὸν δὲ τὸ μὲν πρὸς τῷ Ν κτλ. p. 198,
9 ἐὰν γάρ, καθὼς εἴρηται ἐν τῷ λαʹ θεωρήματι, ἀπὸ τοῦ Ν ὄμματος προσπέσωσιν ἀκτῖνες πρὸς τὴν τοῦ κώνου περιφέρειαν ὡς αἱ ΝΤ, ΝΦ, καὶ ἀπὸ τῶν Τ, Φ
ἐπὶ τὴν κορυφὴν τὴν ∠ ἐπιζευχθῶσιν εὐθεῖαι ὡς αἱ Τ∠, Φ∠, τὸ διὰ τῶν ΝΤ, Τ∠ ἐπίπεδον καὶ τὸ διὰ τῶν ΝΦ, Φ∠ κοινὴν τομὴν ἕξει τὴν ∠Ν, ἐφʼ ἧς ἐὰν τεθῇ τὸ ὄμμα ὡς κατὰ τὸ Ν καὶ τὸ Θ, ἴσον ἀεὶ τοῦ 1 2 κώνου τὸ ὁρώμενον ὀφθήσεται διὰ τὸ λαʹ θεώρημα· ὁμοίως καὶ ἐπὶ τῆς ΛΣ.
ἐπὶ τὴν κορυφὴν τὴν ∠ ἐπιζευχθῶσιν εὐθεῖαι ὡς αἱ Τ∠, Φ∠, τὸ διὰ τῶν ΝΤ, Τ∠ ἐπίπεδον καὶ τὸ διὰ τῶν ΝΦ, Φ∠ κοινὴν τομὴν ἕξει τὴν ∠Ν, ἐφʼ ἧς ἐὰν τεθῇ τὸ ὄμμα ὡς κατὰ τὸ Ν καὶ τὸ Θ, ἴσον ἀεὶ τοῦ 1 2 κώνου τὸ ὁρώμενον ὀφθήσεται διὰ τὸ λαʹ θεώρημα· ὁμοίως καὶ ἐπὶ τῆς ΛΣ.
Ad prop. XXXV.
Scholia in opticorum recensionem Theonis (scholia vetera). Scholia in Euclidem. ed. Johan Ludvig Heiberg, ed. H. Menge. United States. 2018.
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