Proposition 36
Theorem
Two parallelograms (◇ABCD , ◇EFGH ) on equal bases (ᅵBCᅵ = ᅵFGᅵ ) and between the same parallels (BG ‖ AH ) have the same area.
Commentary
Original statement
τὰ παραλληλόγραμμα τὰ ἐπὶ ἴσων βάσϵων ὄντα καὶ ἐν ταῖς αὐταῖς παραλλήλοις ἴσα ἀλλήλοις ἐστίν.
English translation
Parallelograms which are on equal bases and in the same parallels are equal to one another.