Proposition 33b
Construction
On a given line segment to describe a segment of a circle which contains an angle equal to a given right angle.
ἐπὶ τῆς δοθϵίσης ϵὐθϵίας γράψαι τμῆμα κύκλου δϵχόμϵνον γωνίαν ἴσην τῇ δοθϵίσῃ γωνίᾳ ϵὐθυγράμμῳ.
On a given straight line to describe a segment of a circle admitting an angle equal to a given rectilinear angle.