Chapter 3

Question 1

parallel lines

Answer 1

coplanar lines that do not intersect

Question 2

skew lines

Answer 2

non coplanar lines that are not parallel nor intersecting

Question 3

parallel planes

Answer 3

planes that do not intersect

Question 4

theorem 3-1

Answer 4

if 2 parallel lines are cut by a third plane, then the lines of intersection are parallel

Question 5

transversal

Answer 5

line that intersects two or more coplanar lines in unique points

Question 6

alternate interior angles

Answer 6

two nonadjacent interior angles on opposite sides of the transversal

Question 7

same-side interior angles

Answer 7

two interior angles on the same side of the transversal

Question 8

corresponding angles

Answer 8

two angles in corresponding positions relative to the two lines

Question 9

theorem 3-2

Answer 9

if two parallel lines are cut by a transversal, then alternate interior angles are congruent

Question 10

theorem 3-3

Answer 10

if two parallel lines are cut by a transversal, then same-side interior angles are supplementary

Question 11

theorem 3-4

Answer 11

if a transversal is perpendicular to one of two parallel lines, then it is perpendicular to the other one also

Question 12

postulate 11

Answer 12

if two lines are cut by a transversal and corresponding angles are congruent, then the lines are parallel

Question 13

theorem 3-5

Answer 13

if two lines are cut by a transversal and alternate interior angles are congruent, then the lines are parallel

Question 14

theorem 3-6

Answer 14

if two lines are cut by a transversal and same-side interior angles are supplementary, then the lines are parallel

Question 15

theorem 3-7

Answer 15

in a plane two lines perpendicular to the same line are parallel

Question 16

theorem 3-8

Answer 16

through a point outside a line, there is exactly one line parallel to the given line

Question 17

theorem 3-9

Answer 17

through a point outside a line, there is exactly one line perpendicular to the given line

Question 18

theorem 3-10

Answer 18

two lines parallel to a third line are parallel to each other

Question 19

scalene triangle

Answer 19

no sides congruent

Question 20

isosceles triangle

Answer 20

at least two sides congruent

Question 21

equilateral triangle

Answer 21

all sides congruent

Question 22

acute

Answer 22

three acute angles

Question 23

obtuse

Answer 23

one obtuse angle

Question 24

right

Answer 24

one right angle

Question 25

equiangular

Answer 25

all angles congruent

Question 26

theorem 3-11

Answer 26

the sum of the measures of the angles of a triangle is 180

Question 27

third angles theorem

Answer 27

if 2 angles of one triangle are congruent to two angles of another triangle, then the third angles are congruent

Question 28

corollary 2

Answer 28

each angle of an equiangular triangle measure 60

Question 29

corollary 3

Answer 29

in a triangle, there can be at most one right angle or obtuse angle

Question 30

corollary 4

Answer 30

the acute angles of a right triangle are complementary

Question 31

theorem 3-12

Answer 31

the measure of an exterior angle of a triangle equals the sum of the measures of the two remote interior angles

Question 32

polygon

Answer 32

many angles

Question 33

convex polygon

Answer 33

a polygon such that no line containing a side of the polygon contains a point in the interior of the polygon

Question 34

diagonal

Answer 34

segment joining two nonconsecutive vertices

Question 35

theorem 3-13

Answer 35

the sum of the measures of the angles of a convex polygon with n sides is (n-2)180

Question 36

theorem 3-14

Answer 36

the sum of the measures of the exterior angles of any convex polygon, one angle at each vertex, is 360

Question 37

inductive reasoning

Answer 37

• conclusion based on several past observations

- conclusion is probably true, but not necessarily true