- Plane geometry
- 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.
[1913 Webster]
Note: In science, this word (instead of plain) is almost exclusively used to designate a flat or level surface. [1913 Webster]

{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. [1913 Webster]

*The Collaborative International Dictionary of English.
2000.*