[rey-dee-uh n] /ˈreɪ di ən/
the measure of a central angle subtending an arc equal in length to the : equal to 57.2958°.
an SI unit of plane angle; the angle between two radii of a circle that cut off on the circumference an arc equal in length to the radius. 1 radian is equivalent to 57.296 degrees and π/2 radians equals a right angle rad
“angle subtended at the center of a circle by an arc equal in length to the radius,” 1879, from radius.
radian ra·di·an (rā’dē-ən)
A unit of angular measure equal to the angle subtended at the center of a circle by an arc equal in length to the radius of the circle.
A supplementary unit of the International System used in angular measure. One radian is equal to the angle subtended at the center of a circle by an arc equal in length to the radius of the circle, approximately 57°17’44.6″.
[rey-dee-uh ns] /ˈreɪ di əns/ noun 1. brightness or light: the radiance of the tropical sun. 2. warm, cheerful brightness: the radiance of her expression. 3. Rare. . /ˈreɪdɪəns/ noun (pl) -ances, -ancies 1. the quality or state of being radiant 2. a measure of the amount of electromagnetic radiation leaving or arriving at a […]
[rey-dee-uh n-see] /ˈreɪ di ən si/ noun, plural radiancies. 1. .
- Radiant efficiency
noun 1. the ratio of the power emitted by a source of radiation to the power consumed by it ηe
noun, Optics. 1. radiant flux emitted per unit area.