Proposition 29
Theorem
In equal circles, equal arcs (ABC , DEF ) are subtended by equal chords (AC , DF ).
ἐν τοῖς ἴσοις κύκλοις τὰς ἴσας πϵριϕϵρϵίας ἴσαι ϵὐθϵῖαι ὑποτϵίνουσιν.
In equal circles equal circumferences are subtended by equal straight lines.