Triangles, parallels, and area: Book 1 Common Notions
Translations
α΄. Τὰ τῷ αὐτῷ ἴσα καὶ ἀλλήλοις ἐστὶν ἴσα.β΄. Καὶ ἐὰν ἴσοις ἴσα προστεθῇ, τὰ ὅλα ἐστὶν ἴσα.γ΄. Καὶ ἐὰν ἀπὸ ἴσων ἴσα ἀφαιρεθῇ, τὰ καταλειπόμενά ἐστιν ἴσα.δ΄. [Καὶ ἐὰν ἀνίσοις ἴσα προστεθῇ, τὰ ὅλα ἐστὶν ἄνισα.ε΄.Καὶ τὰ τοῦ αὐτοῦ διπλάσια ἴσα ἀλλήλοις ἐστίν.ς΄. Καὶ τὰ τοῦ αὐτοῦ ἡμίση ἴσα ἀλλήλοις ἐστίν.]ζ΄. Καὶ τὰ ἐφαρμόζοντα ἐπ' ἄλληλα ἴσα ἀλλήλοις ἐστίν.η΄. Καὶ τὸ ὅλον τοῦ μέρους μεῖζον [ἐστιν].θ΄. Καὶ δύο εὐθεῖαι χωρίον οὐ περιέχουσιν.
1.Things which equal the same thing are also equal to one another.2. If equals be added to equals, the wholes are equal.3. If equals be subtracted from equals, the remainders are equal.[7] 4. Things which coincide with one another are equal to one another.[8] 5. The whole is greater than the part.