English Dictionary

umbra recta

/ˈʌmbɹə ˈɹɛktə/

noun

On a shadow in the shape of a right triangle, the length of the shadow's edge adjacent to a measured angle.

The building cast an umbra recta on the ground.

意味（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.