Большой англо-русский и русско-английский словарь

subtend an arc

Subtend — Sub*tend , v. t. [imp. & p. p. {Subtended}; p. pr. & vb. n. {Subtending}.] [L. subtendere; sub under + tendere to stretch, extend. See {Tend}.] To extend under, or be opposed to; as, the line of a triangle which subtends the right angle; the… … The Collaborative International Dictionary of English

Arc length — Determining the length of an irregular arc segment is also called rectification of a curve. Historically, many methods were used for specific curves. The advent of infinitesimal calculus led to a general formula that provides closed form… … Wikipedia
subtend — transitive verb Etymology: Latin subtendere to stretch beneath, from sub + tendere to stretch more at thin Date: 1570 1. a. to be opposite to and extend from one side to the other of < a hypotenuse subtends a right angle > b. to fix the angular… … New Collegiate Dictionary
Subtended arc — In geometry, an arc subtended by an angle is a curve whose endpoints are on the angle s two rays. The precise meaning varies with the context. For example, one may speak of the arc of a circumference subtended by an angle whose vertex is a point… … Wikipedia

Visual acuity — 20/15 and 20/15 vision redirect here. For other uses, see 2020 (disambiguation). Typical Snellen chart used for visual acuity testing. Visual acuity (VA) is acuteness or clearness of vision, which is dependent on the sharpness of the retinal… … Wikipedia
Solid angle — The solid angle, Ω , is the angle in three dimensional space that an object subtends at a point. It is a measure of how big that object appears to an observer looking from that point. For instance, a small object nearby could subtend the same… … Wikipedia
Snellen chart — A Snellen chart is an eye chart used by eye care professionals and others to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862.DescriptionThe traditional Snellen chart… … Wikipedia
Reflecting instrument — Reflecting instruments are those that use mirrors to enhance their ability to make measurements. In particular, the use of mirrors permits one to observe two objects simultaneously while measuring the angular distance between the objects. While… … Wikipedia

Nebra sky disk — The Nebra Sky Disk. The Nebra Sky Disk is a bronze disk of around 30 cm diameter, with a blue green patina and inlaid with gold symbols. These are interpreted generally as a sun or full moon, a lunar crescent, and stars (including a cluster… … Wikipedia

Moon illusion — The Moon illusion is an optical illusion in which the Moon appears larger near the horizon than it does while higher up in the sky. This optical illusion also occurs with the sun and star constellations. It has been known since ancient times, and … Wikipedia