umbra recta

名词 n.
中文释义
英 /ˈʌmbɹə ˈɹɛktə/   

英文释义

名词 n.
  1. On a shadow in the shape of a right triangle, the length of the shadow's edge adjacent to a measured angle.
    — Scheubelius a great Mathematician, but by book only, and not by practice who being required ſometime in an Army to make uſe of his Quadrant, knew not the difference between umbra recta, and umbra verſa.

词源

First attested in Modern English in 1688, although the phrase was also used in Middle English by Geoffrey Chaucer (c. 1343–1400) in his Treatise on the Astrolabe; Latin: umbra (“shadow”) + rēcta (feminine nominative singular of rēctus, “straight”) = “straight shadow”; compare umbra versa.
0 次浏览 数据来源: Wiktionary