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Webster 1913 Edition


Tangent

Tan′gent

,
Noun.
[L.
tangens
,
-entis
, p. pr. of
tangere
to touch; akin to Gr. [GREEK] having seized: cf. F.
tangente
. Cf.
Attain
,
Contaminate
,
Contingent
,
Entire
,
Tact
,
Taste
,
Tax
,
Verb.
T.
]
(Geom.)
A tangent line curve, or surface; specifically, that portion of the straight line tangent to a curve that is between the point of tangency and a given line, the given line being, for example, the axis of abscissas, or a radius of a circle produced. See
Trigonometrical function
, under
Function
.
Artificial tangent
, or
Logarithmic tangent
,
the logarithm of the natural tangent of an arc.
–
Natural tangent
,
a decimal expressing the length of the tangent of an arc, the radius being reckoned unity.
–
Tangent galvanometer
(Elec.)
,
a form of galvanometer having a circular coil and a short needle, in which the tangent of the angle of deflection of the needle is proportional to the strength of the current.
–
Tangent of an angle
,
the natural tangent of the arc subtending or measuring the angle.
–
Tangent of an arc
,
a right line, as ta, touching the arc of a circle at one extremity a, and terminated by a line ct, passing from the center through the other extremity o.

Tan′gent

,
Adj.
[L.
tangens
,
-entis
, p. pr.]
Touching; touching at a single point
; specifically
(Geom.)
meeting a curve or surface at a point and having at that point the same direction as the curve or surface; – said of a straight line, curve, or surface;
as, a line
tangent
to a curve; a curve
tangent
to a surface;
tangent
surfaces.
Tangent plane
(Geom.)
,
a plane which touches a surface in a point or line.
–
Tangent scale
(Gun.)
,
a kind of breech sight for a cannon.
–
Tangent screw
(Mach.)
,
an endless screw; a worm.

Webster 1828 Edition


Tangent

TAN'GENT

,
Noun.
[L. tangens, touching. See Touch.]
In geometry, a right line which touches a curve, but which when produced, does not cut it. In trigonometry, the tangent of an arc, is a right line touching the arc at one extremity, and terminated by a second passing through the other extremity.