ξς΄.
γώνιον πρὸς τὸ τρίγωνον λόγον ἔχει δεδομένον.
ἐπεὶ οὖν δοθεῖσά ἐστιν ἡ ὑπὸ τῶν ΒΑΓ γωνία, ἔστι δὲ καὶ ἡ ὑπὸ τῶν ΑΔΒ γωνία δοθεῖσα, καὶ λοιπὴ ἄρα ἡ ὑπὸ ΑΒΔ γωνία δέδοται· δέδοται ἄρα τὸ ΑΕΔ τρίγωνον τῷ εἴδει. λόγος ἄρα ἐστὶ τῆς ΑΒ πρὸς τὴν ΒΔ δοθείς. ὡς δὲ ἡ ΑΒ πρὸς ΒΔ, οὕτως τὸ ὑπὸ
τῶν ΒΑΓ πρὸς τὸ ὑπὸ τῶν ΒΔ, ΑΓ· ὥστε καὶ τοῦ ὑπὸ τῶν ΒΑΓ πρὸς τὸ ὑπὸ τῶν ΒΔ, ΑΓ λόγος ἐστὶ δοθείς. τοῦ δὲ ὑπὸ τῶν ΑΓ ΒΔ πρὸς τὸ ΑΒΓ τρί- γωνον λόγος ἐστὶ δοθείς· καὶ τοῦ ὑπὸ τῶν ΒΑΓ ἄρα πρὸς τὸ ΑΒΓ τρίγωνον λόγος ἐστὶ δοθείς.
Data. Euclid. ed. Johan Ludvig Heiberg, ed. Heinrich Menge. United States. 2016.
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