A point is an exact position or location.

A series of points that goendlessly in both directions.

Line Segment

A part of a line that has two endpoints.

Ray

Ray is the part of a line that has one endpoint and goes on endlessly in the other direction.

PARALLEL LINES

• Def: line that do not intersect.

• Illustration:

• Notation: l || m AB || CD

lm

A

B

C

D

Examples of Parallel Lines• Hardwood Floor

• Opposite sides of windows, desks, etc.

• Parking slots in parking lot

• Parallel Parking

• Streets: Laramie & LeClaire

Examples of Parallel Lines

• Streets: Belmont & School

PERPENDICULAR LINES

• Def: Lines that intersect to form a right angle.

• Illustration:

• Notation: m n

• Key Fact: 4 right angles are formed.

m

n

Ex. of Perpendicular Lines• Window panes

• Streets: Belmont and Cicero

Vertex

The point at which two raysjoin together to form anangle.

Obtuse Angle

An angle that measures morethan 90 degrees.

Acute Angle

An angle that measuresless than 90 degrees.

Right Angle

An angle that measures90 degrees.

Straight Angle

An angle that measures180 degrees.

Degrees

The unit used to measure angles.

7090 11030

Adjacent angles

Two angles are said to be adjacent angles if:1)They have a common vertex.2)They have a common arm.3)The non-common arms lie on either side of the common arms.

• Def: a line that intersects two lines at different points

• Illustration:

Transversal

t

Vertical Angles

• Two angles that are opposite angles.

1 2

3 4

5 6

7 8

t

1 42 35 86 7

Supplementary Angles/Linear Pair

• Two angles that form a line (sum=180)

1 2

3 4

5 6

7 8

t

5+6=1806+8=1808+7=1807+5=180

1+2=1802+4=1804+3=1803+1=180

Corresponding Angles

• Two angles that occupy corresponding positions.

Top Left

t

Top Left

Top Right

Top Right

Bottom Right

Bottom Right

Bottom Left

Bottom Left

1 52 63 74 8

1 2

3 4

5 6

7 8

Alternate Interior Angles

• Two angles that lie between parallel lines on opposite sides of the transversal

t

3 64 5

1 2

3 4

5 6

7 8

Alternate Exterior Angles

• Two angles that lie outside parallel lines on opposite sides of the transversal

t

2 71 8

1 2

3 4

5 6

7 8

Consecutive Interior Angles

• Two angles that lie between parallel lines on the same sides of the transversal

t

3 +5 = 1804 +6 = 180

1 2

3 4

5 6

7 8