Catoptrica (recensio Theonis?)
Euclid
Euclid. Euclidis Opera Omnia, Volume 7. Menge, Heinrich; Heiberg, J.L, editors. Leipzig: Teubner, 1895.
Τὰ πλάγια μήκη ἀπὸ τῶν κυρτῶν ἐνόπτρων, καθάπερ ἐστὶν ἀληθῶς, καὶ φαίνεται.
ἔστω μῆκος τὸ Ε∠, ὄμμα δὲ τὸ Β, ἔνοπτρον δὲ κυρτὸν τὸ ΑΓ, ὄψεις δὲ ἀνακλώμεναι ἐπὶ τὰ Ε, ∠. τὰ δὲ ἄλλα τὰ αὐτά.