Geometry Vocabulary Ch. 3

Front 1

If two lines cut by a transversal are parallel, then corresponding angles are _____

Back 1

Corresponding Angles Postulate

Front 2

If two lines cut by a transversal are parallel, then alternate interior angles are ____.

Back 2

Alternate Interior Angles Theorem

Front 3

If two lines cut by a transversal are parallel, then alternate exterior angles are _____.

Back 3

Alternate Exterior Angles Theorem

Front 4

If two lines cut by a transversal are parallel, then same side interior angles are _________.

Back 4

Same-Side Interior Angles Theorem

Front 5

If two lines cut by a transversal in such a way that corresponding angles are congruent, then two lines are ______.

Back 5

Converse of the Corresponding angles postulate

Front 6

If two lines are cut by a transversal in such a way that corresponding angles are congruent, then the two lines are _________.

Back 6

Converse of the Same-Side Interior Angles Theorem

Front 7

If two lines are cut by a transversal in such a way that alternate interior angles are congruent, then the two lines are_____

Back 7

Converse of the Alternate Interior Angles Theorem

Front 8

If two lines are cut by a transversal in such way that the alternate exterior angles are congruent, then the two lines are_____.

Back 8

Converse of the Alternate Exterior Angles Theorem

Front 9

Theorem
(coplanar)

Back 9

If two coplanar lines are perpendicular to the same line, then the two lines are parallel.

Front 10

Theorem
(Parallel)

Back 10

If two lines are parallel to the same line, then the two lines are parallel.

Front 11

The parallel postulate
(one and only one)

Back 11

Given a line and a point not on the line, there is only one line that contains the given point and is parallel to the given line.

Front 12

Triangle Sum Theorem
(sum of all the angles in a triangle)

Back 12

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

Front 13

Exterior Angle Theorem
(equal to the sum)

Back 13

The measure of an exterior angle of a triangle is equal to the sum of the measures of the remote interior angles

Front 14

Sum of the Interior Angles of a Polygon
(equation)

Back 14

s=(n-2)180

Front 15

The Measure of an Interior Angle of a Regular Polygon
(equation)

Back 15

m=180-360/n

Front 16

Sum of the Exterior Angles of a Polygon
(3 digit number)

Back 16

360

Front 17

Parallel Lines Theorem

Back 17

In a coordinate plane, two non vertical lines are parallel if and only if they have the same slope

Front 18

Perpendicular lines theorem

Back 18

In a coordinate plane, two non vertical lines are perpendicular if and only if the product of their slopes is -1

Front 19

Alternate exterior angles
(cut by a)

Back 19

When two parallel lines are cut by a transversal, the two pairs of angles on opposite sides of the transversal and outside the parallel lines, and the angles in each pair are congruent

Front 20

Alternate interior angles
(cut by a)

Back 20

When two lines are crossed by another line (which is called the Transversal), the pairs of angles on opposite sides of the transversal but inside the two lines are called Alternate Interior Angles.

Front 21

axis of symmetry
(rotates around)

Back 21

an object with rotational symmetry, also known in biological contexts as radial symmetry, is an object that looks the same after a certain amount of rotation

Front 22

center of a regular polygon
(regular means)

Back 22

The point inside a regular polygon that is equidistant from each vertex

Front 23

central angle of a regular polygon
(central)

Back 23

an angle at the centre of the polygon.

Front 24

concave polygon
(vs convex)

Back 24

a polygon such that there is a straight line that cuts it in four or more points

Front 25

convex polygon
(vs concave)

Back 25

a polygon such that no side extended cuts any other side or vertex; it can be cut by a straight line in at most two points

Front 26

corresponding angles
(shares)

Back 26

the angles that occupy the same relative position at each intersection where a straight line crosses two others. If the two lines are parallel, the corresponding angles are equal

Front 27

equiangular polygon
(all angles are)

Back 27

polygon whose vertex angles are equal. If the lengths of the sides are also equal then it is a regular polygon.

Front 28

equilateral polygon
(all sides are)

Back 28

an equilateral polygon is a polygon which has all sides of the same length.

Front 29

midsegment of a trapezoid
(in the middle)

Back 29

a convex quadrilateral with at least one pair of parallel sides is referred to as a trapezoid

Front 30

mid segment of a triangle
(in the middle)

Back 30

is a segment that connects the midpoints of two sides of the triangle.

Front 31

parallelogram
(all sides are…)

Back 31

All sides are parallel

Front 32

polygon
(no curves, more than 2)

Back 32

a plane figure with at least three straight sides and angles, and typically five or more.

Front 33

quadrilateral
(four sides)

Back 33

4 sided figure

Front 34

rectangle
(all ____ lines)

Back 34

a plane figure with four straight sides and four right angles, esp. one with unequal adjacent sides, in contrast to a square.

Front 35

reflectional symmetry
(reflect over)

Back 35

Reflection symmetry, line symmetry, mirror symmetry, mirror-image symmetry, or bilateral symmetry is symmetry with respect to reflection.

Front 36

regular polygon
(regular)

Back 36

a polygon with all sides and all angles equal

Front 37

remote interior angle
(non-adjacent)

Back 37

Non-adjacent interior angles

Front 38

rhombus
(acute <s)

Back 38

parallelogram with opposite equal acute angles, opposite equal obtuse angles, and four equal sides.

Front 39

rotational symmetry
(Rotates and still remains symmetric)

Back 39

an object with rotational symmetry, also known in biological contexts as radial symmetry, is an object that looks the same after a certain amount of rotation.

Front 40

same-side interior angles
(angles on the same side)

Back 40

Another name fo consecutive interior angles.

Front 41

slope
(down, degree)

Back 41

of a surface or line be inclined from a horizontal or vertical line; slant up or down

Front 42

square
(all sides are….)

Back 42

a plane figure with four equal straight sides and four right angles.

Front 43

transversal
(If two lines are cut by a)

Back 43

intersecting a system of lines.

Front 44

trapezoid
(one set of ____ lines)

Back 44

a quadrilateral with only one pair of parallel sides.