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In geometry, formal interpretations are created using other identified words or terms. There are, however, three words in geometry that are not formally defined. This words space point, line and plane, and are described as the "three undefined regards to geometry".

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While this words space "undefined" in the officially sense, we have the right to still "describe" this words. The descriptions, proclaimed below, refer to these native in relationship to geometry.

POINT • a suggest indicates a ar (or position) in space. • a allude has no dimension (actual size). • a point has no length, no width, and no height (thickness). • a suggest is usually named with a capital letter. • in the coordinate plane, a point is called by an bespeak pair, (x,y). if we represent a allude with a dot, the dot have the right to be very tiny or really large. Remember, a allude has no size.
The size of the dot attracted to stand for a allude makes no difference. Points have no size. They simply represent a location.
LINE (straight line) • a line has actually no thickness. • a line"s length extends in one dimension. • a line goes ~ above forever in both directions. • a line has actually infinite length, zero width, and zero height. • a heat is assumed to be straight. • a line is drawn with arrow head on both ends. • a line is called by a single lowercase script letter, or by any two (or more) points i beg your pardon lie on the line.
Lines have the right to be labeled with a single script letter, or by 2 points top top the line,
. The thickness of a line renders no difference.

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PLANE • a airplane has two dimensions. • a plane forms a level surface expanding indefinitely in all directions. • a aircraft has unlimited length, infinite width and also zero elevation (thickness). • a airplane is attracted as a four-sided figure resembling a tabletop or a parallelogram. • a plane is called by a solitary letter (plane m) or by 3 coplanar, however non-collinear,* point out (plane ABC).
airplane m or aircraft ABC. If the chart of a plane has edges, you should remember that the aircraft actually has actually no boundaries.
* collinear points room points that lie ~ above the same straight line. Coplanar points are points that line in the very same plane.

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