**The Collaborative International Dictionary of English v.0.48:**

Plane \Plane\, a. [L. planus: cf. F. plan. See Plan, a.]
Without elevations or depressions; even; level; flat; lying
in, or constituting, a plane; as, a plane surface.
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Note: In science, this word (instead of plain) is almost
exclusively used to designate a flat or level surface.
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Plane angle, the angle included between two straight lines
in a plane.
Plane chart, Plane curve. See under Chart and Curve.
Plane figure, a figure all points of which lie in the same
plane. If bounded by straight lines it is a rectilinear
plane figure, if by curved lines it is a curvilinear plane
figure.
Plane geometry, that part of geometry which treats of the
relations and properties of plane figures.
Plane problem, a problem which can be solved geometrically
by the aid of the right line and circle only.
Plane sailing (Naut.), the method of computing a ship's
place and course on the supposition that the earth's
surface is a plane.
Plane scale (Naut.), a scale for the use of navigators, on
which are graduated chords, sines, tangents, secants,
rhumbs, geographical miles, etc.
Plane surveying, surveying in which the curvature of the
earth is disregarded; ordinary field and topographical
surveying of tracts of moderate extent.
Plane table, an instrument used for plotting the lines of a
survey on paper in the field.
Plane trigonometry, the branch of trigonometry in which its
principles are applied to plane triangles.
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**The Collaborative International Dictionary of English v.0.48:**

Trigonometry \Trig`o*nom"e*try\, n.; pl. -tries. [Gr. ? a
triangle + -metry: cf. F. trigonom['e]trie. See Trigon.]
1. That branch of mathematics which treats of the relations
of the sides and angles of triangles, which the methods of
deducing from certain given parts other required parts,
and also of the general relations which exist between the
trigonometrical functions of arcs or angles.
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2. A treatise in this science.
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Analytical trigonometry, that branch of trigonometry which
treats of the relations and properties of the
trigonometrical functions.
Plane trigonometry, and Spherical trigonometry, those
branches of trigonometry in which its principles are
applied to plane triangles and spherical triangles
respectively.
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