geomentry unit 1:
parallel lines
2 coplanar lines that have no points in common or identical
opposite rays
__> __> ab and ac are opposite rays if and only if a is between b and c
betweenness of #s
a # is between 2 other #s if it is greater than one of them and less than the other
pixels
a dot on a tv, computer screen, or other monitor
oblique line
a line that is neither horizontal nor vertical
vertical line
a line with an equation x=h on the coordinate plane
horizontal line
a line with an equation y=k on the coordinate plane
menu
a list of options from which a user of a dynamic geometry system (DGS) can select an operation for the DGS to perform
transversable network
a network in which all the arcs may be traced exactly once without picking up the tracing instrument
even node
a node that is the endpoint of an even # of arcs in a network
odd node
a node that is the endpoint of an odd # of arcs in a network
arc
a path from one point (node) of a network to another point
betweenness of points
a point is between 2 other points on the same line if its coordinate is between their coordinates
figure
a set of points
plane figure
a set of points that all in one plane
three-dimensional
a space type of geometry of figure in which all points do not lie on the same line in a single plane
one-dimensional
a space type of geometry or figure in which all points are collinear
two-dimensional
a space type of geometry or figure in which all points are coplanar
postulate
a statement assumed to be true
theorem
a statement that follows from postulate definitions and other statements already proven
undefined terms
a term used without a specific mathematical definition
network
a union of points (its vertices, or nodes) and segment(its arc) connecting them. Also called graph
distance between 2 points
absolute value of the difference of the coordinates of the points on a coordinated line
node
an endpoint of an arc in a network. Also called vertex
standard form of an equation of a line
an equation of a line in the form ax+by=c, where a and b are not both 0
dynamic geometry system
any calculator or computer utility that enables the user to draw of construct figures and then dynamically manipulate them
slope
in the coordinate plane, the change in y-values divided by the corresponding change in x-values
y-intercept
in the equation of a line, the value of y when x=0
coordinatized line
line on which every point is identified with exactly 1 # and every # identified with a point on the line
slope intercept form of an equation of a line
linear equation of the form y=mx+b where m is the slope and b is the y-intercept
discrete line
lines made up of discrete points
discrete point
points described as dots
coplanar points
points lying in the same plane
collinear points
points that lie on the same line
vertices, vertex
see angle, network, polygon
endpoints
see arc, ray segment
circularity
the "circling back" that sometimes occurs when one tries to define basic terms, returning to the word that one id trying to define
coordinate
the # or #s associated with the location of a point on a line , a plane, or in space
window
the area in which a dynamic geometry system (DGS) can draw
euclidean geometry
the collection of propositions about figures that includes or from which can be deduced those given by mathematician euclid around 250 bcd
graph theory
the geometry of networks
segment, line segment
the set consisting of the distinct point a and b (endpoints)and all points ___ between a and b denoted AB also called line segment
ray
the set consisting of the distinct points a (its endpoint) and b, all points for which b is between the pout and a denoted ___> ab
space
the set of all points in a geometry
discrete geometry
the study of discrete points and lines
plane coordinate geometry
the study of geometric figures using points as ordered pairs of real #s
