Glencoe McGraw-Hill Geometry Chapter 1

acute angle

An angle with a degree measure less than 90.

adjacent angles

Two angles that lie in the same plane, have a common vertex and a common side, but no common interior points.

angle

The intersection of two noncollinear rays at a common endpoint.

angle bisector

A ray that divides an angle into two congruent angles.

area

The number of square units needed to cover a surface.

base

Face of a shape.

between

For any two points A and B on a line, there is another point C between A and B if and only if A, B, and C are collinear and AC+CB= AB.

circumfrence

The distance around a circle.

collinear

Points that lie on the same line.

complementary angles

Two angles with measures that have a sum of 90.

concave

A polygon for which there is a line containing a side of the polygon that also contains a point in the interior of the polygon.

cone

A solid with a circular base, a vertex not contained in the same plane as the base, and a lateral surface area composed of all points in the segments connecting the vertex to the edge of the base.

congruent

Having the same measure.

construction

A method of creating geometric figures without the benefit of measuring tools. Generally only a pencil, straightedge, and compass are used.

convex

A polygon for which there is no line that contains both a side of the polygon and a point in the interior of the polygon.

coplanar

Points that lie in the same plane.

cylinder

A figure with bases that are formed by congruent circles in parallel planes.

degree

A unit of measure used in measuring angles and arcs. An arc of a circle with a measure of 1 degree is 1/360 of the entire circle.

distance

The length of the segment between two points.

edge

A line that connects two nodes in a network.

equilateral polygon

A polygon with all congruent sides.

equiangular polygon

A polygon with all congruent angles.

exterior

A point is in the exterior of an angle if it is neither on the angle nor in the interior of the angle.

face

A flat surface of a polygon.

interior

A point is in the interior of an angle if it does not lie on the angle itself and it lies on a segment with endpoints that are on the sides of the angle.

intersection

A set of points common to two or more geometric figures.

line

Is made up of points and has no thickness or width.

linear pair

A pair of adjacent angles whose non-common sides are opposite rays.

line segment

A measurable part of a line that consists of two points, called endpoints, and all of the points between them.

midpoint

The point on a segment exactly halfway between the endpoints of the segment.

n-gon

A polygon with n sides.

obtuse angle

An angle with degree measure greater than 90 and less than 180.

opposite rays

Two rays, ray BA and ray BC such that B is between A and C.

perimeter

The sum of the lengths of the sides of a polygon.

perpendicular

Lines that form right angles.

plane

A flat surface made up of points that has no depth and extends indefinitely in all directions.

Platonic solid

The five regular polyhedra: tetrahedron, hexahedron, octahedron, dodecahedron, or icosahedron.

point

A location, represented by a dot, named by capital letters.

polygon

A closed figure formed by a finite number of coplanar segments called sides such that the following conditions are met:

1. The side that have a common endpoint are noncollinear.

2. Each side intersects exactly two other sides, but only at their endpoints, called the vertices.

polyhedron

Closed 3-dimensional figures made up of flat polygonal regions.

prism

A polyhedron with two parallel congruent faces called bases connected by parallelogram faces.

pyramid

A polyhedron that has a polygonal base and three or more triangular faces that meet at a common vertex.

ray

Part of a line, it has one endpoint and extends indefinitely in one direction.

regular polygon

A convex polygon in which all of the sides are congruent and all of the angles are congruent.

regular polyhedron

A polyhedron in which all of the faces are regular congruent polygons.

right angle

An angle with a degree measure of 90.

segment bisector

A segment, line, or plane that intersects a segment at its midpoint.

side

The rays of an angle.

space

A boundless 3-dimensional set of all points.

sphere

In space, the set of all points that are a given distance from a given point, called the center.

supplementary angle

Two angles with measures that have a sum of 180.

surface area

The sum of the areas of all faces and side surfaces of a 3-dimensional figure.

undefined term

Words, usually readily understood, that are not formally explained by means of more basic words and concepts.

vertex

The common endpoint of an angle.

vertex of a polygon

The vertex of each angle of a polygon.

vertical angles

Two nonadjacent angles formed by two intersecting lines.

volume

A measure of the amount of space enclosed by a 3-dimensional figure.