History
There is nothing extant of the writing of Thales; work done in ancient Greece tended to be attributed to men of wisdom without respect to all the individuals involved in any particular intellectual constructions — this is true of Pythagoras especially. Attribution did tend to occur at a later time, Reference to Thales was made by Proclus, and by Diogenes Laertius documenting Pamphila statement that the ancient
| “ | was the first to ascribe a right-angle triangle within a circle (Thomas 2002) | ” |
Indian and Babylonian mathematicians knew this for special cases before Thales proved it. It is believed that Thales learned that an angle inscribed in a semicircle is a right angle during his travels to Babylon. The theorem is named after Thales because he was said by ancient sources to have been the first to prove the theorem, using his own results that the base angles of an isosceles triangle are equal, and that the sum of angles in a triangle is equal to two right angles.
- o se del mezzo cerchio far si puote
- triangol sì ch'un retto non avesse.
- Or if in semicircle can be made
- Triangle so that it have no right angle.
Dante's Paradiso (canto 13, lines 101–102) refers to Thales' theorem in the course of a speech.
Read more about this topic: Thales' Theorem
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