Download Chapter 1 Vocabulary

Chapter 1 Vocabulary
Section 1.1-1.3
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Undefined terms – words that do not have a formal definition, but there is an
agreement about what they mean.
Point - Has no actual size, used to represent an object or location in space
Line - Has no thickness or width, used to represent a continuous set of linear
points that extend indefinitely in both directions
Plane - Has no thickness, width, or depth, used to represent a flat surface that
extends indefinitely in all directions.
Collinear - Set of points, that all lie on the same line (Hint: Two points are
always collinear. Three points must be checked to determine if they are
collinear.)
Non-collinear - Set of points, that do not all lie on the same line
Coplanar - Set of points, or lines, that lie in the same plane (Hint: Three points
are always coplanar. Four points must be checked to determine if they are
coplanar.)
Non-coplanar – Set of points, or lines, that do not lie in the same plane
Defined terms – terms that can be described using known words such as point
or line
Line segment – portion of a line with two end points
Endpoints – points that show a start or stopping point for a segment
Ray - portion of a line with one end point
Opposite rays – rays with a common endpoint that are going in opposite
directions.
Intersections – where two or more geometric figures intersect if they have one
or more points in common
Postulate – a rule that is accepted without proof
Axiom – a rule that is accepted without proof
Coordinate – the real number that corresponds to a point
Distance - A measurement of how far through space
Between – when three points line on a line, you can say that on point is
between the other two.
Congruent - equal measures
Midpoint – a point that divides, or bisects, a segment into two congruent
segments
Segment Bisector – The line that divides something into two equal parts
Section 1.4 – 1.6
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Angle – formed by Two rays that meet at a point and extend indefinitely
Sides – the rays of an angle
Vertex – the point at which to rays meet
Measure – the number that represents a degree of an angle
Right angle - angles measure exactly 90 degrees. Perpendicular lines form right
angles.
Acute angle - angles measure more than 0 degrees but less than 90 degrees.
Obtuse angle - angles measure greater than 90 degrees but less than 180
degrees.
Straight angle - angle (line) has a measure of 180 degrees.
Congruent angles – two angles that have the same measure
Angle bisector – a ray that divides an angle into two angles that are congruent
Adjacent angles - Coplanar angles that have a common vertex and one
common side, but no common interior points
Vertical angles - Two non-adjacent angles formed by two intersecting lines
Linear pair - Two adjacent angles whose non-common sides are two rays going
in opposite direction
Complementary angles - Sum of the measures of the two angles is 90 degrees.
Supplementary angles - Sum of the measures of the two angles is 180 degrees.
Polygon – a closed plan figure with three or more line segments called sides
and each side intersects exactly two sides, one at each endpoint, so that no
two sides with a common endpoint are collinear.
Convex Polygon – if not line that contains a side of the polygon contains a
point in the interior of the polygon
Concave Polygon – a polygon that has sides containing points in the interior of
the polygon.
n-gon – a polygon with more than 12 sides, 13-gon, 50-gon
Equilateral Polygon – all sides are the same
Equiangular Polygon – all angles are the same
Regular – All sides and angles are the same
Parallel – Two coplanar lines that do not intersect
Skew - Two non-coplanar lines that do not intersect
Length - How far from end to end
Parallel lines - coplanar lines that do not intersect
Perpendicular lines – lines that intersect to form a right angle