Chapter 1

Question 1

space

Answer 1

set of all points

Question 2

collinear points

Answer 2

points all in one line

Question 3

coplanar points

Answer 3

points all in one plane

Question 4

ruler postulate

Answer 4

• points on a line can be paired with the real numbers in such a way that any two points can have coordinates 0 and 1
• once a coordinate system has been chosen in this way, the distance between any two points equals the absolute value of the difference of their coordinates

Question 5

segment addition postulate

Answer 5

if B is between A and C, then AB+BC=AC

Question 6

congruent

Answer 6

two objects that have the same size and shape

Question 7

congruent segments

Answer 7

segments that have equal lengths

Question 8

midpoint of a segment

Answer 8

the point that divides the segment into two congruent segments

Question 9

bisector of a segment

Answer 9

a line, segment, ray, or plane that intersects the segment at its midpoint

Question 10

angle

Answer 10

the figure formed by two rays that have the same endpoint

Question 11

sides

Answer 11

two rays of the angle

Question 12

vertex

Answer 12

common endpoint of two rays

Question 13

acute angle

Answer 13

measures between 0 and 90

Question 14

right angle

Answer 14

measures 90

Question 15

obtuse angle

Answer 15

measures between 90 and 180

Question 16

straight angle

Answer 16

measures 180

Question 17

protractor postulate

Answer 17

rays of an angle can be paired with the real numbers from 0 to 180

Question 18

angle addition postulate

Answer 18

• if point B lies in the interior of angle AOC, then angle AOB plus angle BOC = AOC
• if angle AOC is a straight angle and B is any point not on line AC, then AOB+BOC=180

Question 19

congruent angles

Answer 19

angles that have equal measures

Question 20

adjacent angles

Answer 20

two angles in a plane that have a common vertex and a common side but no common interior points

Question 21

bisector of an angle

Answer 21

the ray that divides the angle into two congruent adjacent angles

Question 22

postulate about number of points

Answer 22

a line contains at least two points; a plane contains at least three points not all in one line; space contains at least four points not all in one plane

Question 23

postulate about points on a line

Answer 23

through any two points there is exactly one line

Question 24

postulate about three points and a plane

Answer 24

through any three points there is at least one plane, and through any three noncollinear points there is exactly one plane

Question 25

postulate about two points and a plane

Answer 25

if two points are in a plane, then the line that contains the points is in that plane

Question 26

postulate about planes intersecting

Answer 26

if two planes intersect, then their intersection is a line

Question 27

theorem 1-1

Answer 27

if two lines intersect, then they intersect in exactly one point

Question 28

theorem 1-2

Answer 28

through a line and a point not in the line there is exactly one plane

Question 29

theorem 1-3

Answer 29

if two lines intersect, then exactly one plane contains the lines