2 α΄. Ἔστωσαν δύο εὐθεῖαι αἱ ΑΒ ΑΓ πρὸς ὀρθὰς ἀλλήλαις, καὶ ἤχθω ἀπὸ τοῦ Β τῇ ΑΓ παράλληλος ἡ Β∠, καὶ κείσθω τῇ ΑΒ· ἴδη ἡ Β∠, καὶ ἐπεζεύχθω ἡ ∠Γ, καὶ συμπιπτέτω τῇ ΒΑ κατὰ τὸ Ε, καὶ ἀπὸ τοῦ Ε τῇ ΑΓ παράλληλος ἡ ΕΘ, καὶ ἐκβεβλήσθω ἡ Β∠, καὶ ἤχθω ἀπὸ τοῦ ∠ τῇ ΒΕ παράλληλος ἡ ∠Η, καὶ κείσθωσαν τῇ Β∠ ἴσαι αἱ ∠Ν ΝΛ ΛΞ ΞΚ καὶ διὰ τῶν Ν Λ Ξ Κ σημείων τῇ ΒΕ παράλληλοι αἱ ΝΟ ΛΜ ΞΠ ΚΘ καὶ κείσθω τῇ ΒΑ ἴση ἡ ΚΡ, καὶ τετμήσθω δίχα ἡ ΚP κατὰ τὸ Σ, καὶ ὡς ἡ ΚΘ πρὸς ΘΣ, οὕτως ἡ ΣΘ πρὸς ΘΤ, ὡς δέ ἡ ΣΘ πρὸς ΘΤ, οὕτως ἡ ΘΤ πρὸς ΘΦ, καὶ ἀφῃρήσθω ἀπὸ τῆς ΞΠ τῇ ΑΒ ἴση ἡ ΧΞ, καὶ ἐπεζεύχθω ἡ ΧΚ καὶ ἡ ΚΦ καὶ ἀπὸ τοῦ Σ τῇ XΦ παράλληλος ἡ ΣΨ, ὑπὸ δὲ τοῦ Ψ τῇ ΚΞ παράλληλος ἡ ΨΩ, καὶ ἔστω ὡς ΛΜ πρὸς ΜΩ, οὕτως ἡ ΩΜ πρὸς ΜΑ. ὡς δὲ ἡ ΩΜ πρὸς ΜΑ, οὕτως ἡ ΑΜ πρὸς ΜΒ, καὶ ἀφῃρήσθω ἀπὸ τῆς ΟΝ τῇ ΑΒ ἴση ἡ ΝΓ, καὶ ἐπεζεύχθω ἡ ΓΛ καὶ ἡ ΓΒ, καὶ ἤχθω ἀπὸ τοῦ Ω τῇ ΒΓ παράλληλος ἡ Ω∠, ἀπὸ δέ τοῦ ∠ τῇ ΛΝ παράλληλος ἡ ΛΕ, καὶ ἔστω ὡς ἡ ∠Η πρὸς ΗΕ, οὕτως ΗΕ πρὸς ΗΖ, ὡς δὲ ἡ ΕΗ πρὸς ΗΖ, οὕτως ἡ ΖΗ πρὸς ΗΘ, καὶ ἐπεζεύχθω ἡ ΘΓ, καὶ ἤχθωσαν τῇ ΘΓ παράλληλοι αἱ ΖΚ ΕΛ, καὶ ἀπὸ τῶν Κ Λ ταῖς ΑΓ B∠ παράλληλοι αἱ ΚΜ ΛΝ δεῖξαι ὅτι τῶν ΑΓ Β∠ υέσαι ἀνάλογόν εἰσιν αἱ ΜΚ ΝΛ.