"In geometry the following theorems are attributed to him [Thales]—and their character shows how the Greeks had to begin at the very beginning of the theory—(1) that a circle is bisected by any diameter (Eucl. I., Def. 17), (2) that the angles at the base of an isosceles triangle are equal (Eucl. I., 5), (3) that, if two straight lines cut one another, the vertically opposite angles are equal (Eucl. I., 15), (4) that, if two triangles have two angles and one side respectively equal, the triangles are equal in all respects (Eucl. I., 26). He is said (5) to have been the first to inscribe a right-angled triangle in a circle: which must mean that he was the first to discover that the angle in a semicircle is a right angle. He also solved two problems in practical geometry: (1) he showed how to measure the distance from the land of a ship at sea (for this he is said to have used the proposition numbered (4) above), and (2) he measured the heights of pyramids by means of the shadow thrown on the ground (this implies the use of similar triangles in the way that the Egyptians had used them in the construction of pyramids)."
Quote Details
Added by wikiquote-import-bot
Unverified quote
0 likes
Mathematicians from EnglandAcademics from the United KingdomNon-fiction authors from EnglandHistorians of scienceHistorians of mathematics
Original Language: English
Available Languages (1)
Sources
Imported from EN Wikiquote
https://en.wikiquote.org/wiki/Thomas_Little_Heath
Revision History
No revisions have been submitted for this quote.
Categories
Thomas Little Heath
48 quotes on TrueQuotesView all quotes by Thomas Little Heath →
Related Quotes
"The most probable view is that adopted by Nesselmann, that the works which we know under the three titles formed part…"
"It may be in some measure due to the defects of notation in his time that Diophantos will have in his solutions no nu…"
"Nesselmann observes that we can, as regards the form of exposition of algebraic operations and equations, distinguish…"
"An edition is... still wanted which shall, while in some places adhering... to the original text, at the same time be…"
"Any satisfactory reproduction of the Conics must fulfil certain essential conditions: (1) it should be Apollonius and…"
"There is perhaps no question that occupies, comparatively, a larger space in the history of Greek geometry than the p…"
"Theodorus of Cyrene and Theaetetus generalised the theory of irrationals, and we may safely conclude that a great par…"
"While then for a long time everyone was at a loss, Hippocrates of Chios was the first to observe that, if between two…"
"The discovery of Hippocrates amounted to the discovery of the fact that from the relation (1)\frac{a}{x} = \frac{x}{y…"
"Diophantos lived in a period when the Greek mathematicians of great original power had been succeeded by a number of …"