arc·​length | \ (ˌ)ärk-ˈleŋ(k)th How to pronounce arclength (audio) , -ˈlen(t)th \
plural arclengths

Definition of arclength

: the length of a segment of an arc Thus, in a unit circle (radius = 1), any angle of 1 radian cuts off an arc of unit length. All other arclengths are proportional to this; for instance, doubling the radius (to 2) and tripling the angle (to 3 radians) yields an arclength of 6.— Rheta N. Rubenstein et al., Math Horizons, November 2003

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First Known Use of arclength

1849, in the meaning defined above

History and Etymology for arclength

arc entry 1 + length

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The first known use of arclength was in 1849

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Cite this Entry

“Arclength.” Dictionary, Merriam-Webster, Accessed 16 Apr. 2021.

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