Angle Relationships

Lesson Objective

Discover relationships between special pair of angles.

Vocabulary. Adjacent angles, linear pair angles, vertical angles

Adjacent angles are two angles that lie in the same plane, have a common vertex, and a common side, but no common interior points.

AC

B

D

ACB

D

A C

B

D

Examples

No example

A Linear pair is a pair of adjacent angles whose noncommon sides are opposite ray

ACB

D

Example No example

AC

B D

B,D, and C are no collinear

Vertical angles are angles opposite to one another at the intersection of two lines. (vertical angles are congruent)

E C

B

D

A

CB

D

Examples No example

A

Geogebra

Supplementary angles:Two angles that add up to 180°

ACB

∠BDA and ADC∠are supplementary

AB

D

0100 080 ∠A and B∠are supplementary

Complementary angles: Two angles that add up to 90°

ZR

P Q

2

∠1 and 2 are ∠complementary

∠ PQR and XYZ are ∠complementary

YX0401 050

The little symbol       ("corner") is used to indicate a right angle.

is read perpendicular to

C

B D

A

BCAD

Perpendicular lines meet to form right angles