Does παρατίθημι mean "prove" in Greek geometry?

Question

The scientifically minded Luke wrote in Acts 17:3

διανοίγων καὶ παρατιθέμενος ὅτι τὸν χριστὸν ἔδει παθεῖν καὶ ἀναστῆναι ἐκ νεκρῶν, καὶ ὅτι οὗτός ἐστιν ὁ χριστός, ὁ Ἰησοῦς ὃν ἐγὼ καταγγέλλω ὑμῖν.

Acts 17:3 New International Version

explaining and proving that the Messiah had to suffer and rise from the dead. "This Jesus I am proclaiming to you is the Messiah," he said.

New American Standard Bible

explaining and giving evidence that the Christ had to suffer and rise again from the dead, and saying, "This Jesus whom I am proclaiming to you is the Christ."

The Greek word was: G3908. παρατίθημι (paratithémi) Did it mean "prove" in secular Greek writings, particularly math writings?Was there another Greek word for “prove” in Euclid's Elements?

Answer 1

παρατίθημι (paratithémi) in Acts 17:3 is Verb - Present Participle Middle - Nominative Masculine Singular. Note the middle voice!

The meaning of this word is given four basic meanings by BDAG, only three of which occur in the NT. The primary meaning is "place beside, place before". More specifically, BDAG's first two meanings are:

1. to place something before someone, set before, frequently of food; eg, Mark 6:41, 8:6, Luke 9:16, etc.
2. to set forth in teaching (a) in the active voice - put before, eg, Matt 13:24, 31. (b) in middle voice - demonstrate, point out; eg, Acts 17:3, 28:23.

Thus, "prove" here might be a bit too strong but "demonstrate" and strongly "point out", or, "place the evidence before you" is about the right meaning in Acts 17:3.

APPENDIX - "Prove" in Greek Geometry

The word (or phrase) placed at the end of a Greek geometrical proof was ὅπερ ἔδει δεῖξαι = it has been demonstrated/proved. Note that this is quite different from the word above. In Latin this was "quod erat demonstrandum".

Answer 2

The formal word "prove" used by mathematicians today does not really have a single Greek equivalent.

From http://farside.ph.utexas.edu/Books/Euclid/Elements.pdf (Thanks, Nigel for the pointer.), there are three Greek words translated into the English word "prove". There are

1. δειχθήσεται to show
2. προτεθείσῃ to imply
3. συναποδέδεικται to accept

The biblical word παρατίθημι is not in Euclid at all. I agree with Dottard that παρατίθημι does not carry the strong sense of prove mathematically.