undefined terms

 points, lines, and planes

point

is a location usually reprsented by a dot or a capital letter.

ex. point R ^or R•

Line

has two arrows, one at each end indicating that it extends infinitly in both directions

↔

postulate

is an accepted statement of fact

1st postulate

through any 2 points, there is exactly one line.

collinear

points that lie on the same line

noncollinear

points that do not lie on tha same line.

plane

can be thought as a flat surface that extends infinitly

Coplanar

points that lie on the same plane.

noncoplanar

points that do not lie in the same plane.

2nd postulate

two lines intersect at exactly one line.

3rd postulate

two planes intersect at exactly one line.

4th postulate

through any three noncollinear points there is exaactly one plane.

Space

a boundless three deminsional set of all points

Ray

has exactly one endpoint and extends infinitely in one direction.

Opposite rays

rays that are going in the opposite direction.

parallel lines

two or more lines that extend infinitely in both directions and never intersect.

skew lines

lines that are neither parallel nor perpendicular and lie in different planes.

parallel planes

planes that do not intersect 

line segment

a part of a line

between

a point is between two points if three points are collinear.

approximate value:

use pi in your calculator

exact value:

your answer in terms of pi

between

a point is between two points if the three points are collinear.

congruent segments

segments that have the same measure

segment bisector

a line, segment or ray that goes through a segment and divided it into two smaller, congruent segments

 acute angle

an angle that has a measure less than 90 degrees

obtuse angle

an angle that has a measure of more than 90 degrees

right angle

an angle that measures exactly 90 degrees

straight angle

an angle that measures exactly 180 degrees

congruent angles

two angle that have the same measure

angle bisector

divides an angle into two smaller, congruent angles

perpendicular lines

two lines that intersect to form right angles

perpendicular bisector

a line, segment or ray that is perpendicular to the segment at its midpoint.