Define Adjacent Angles:

Construct two intersecting line segments, AB and CD.

Choose each segment and construct "point at intersection", label as point E.

State the four sets of adjacent angles that are formed.

is adjacent to and .

is adjacent to and .

is adjacent to and .

is adjacent to and .

= = = =

What can you conclude about and ?

and and ?

These sets of angles are called "vertical angles".

Define Vertical Angles:

What can you conclude about and ?

These angles form a "linear pair".

Define a Linear Pair of Angles:

How many sets of linear pairs are formed with two intersecting lines?

Construct a line segment AB.

Choose this segment and construct "point on object", label as point C.

Construct line segment CD.

= =

What can you conclude about the sum of these two angles?

Move point D around the screen, does your conclusion stay the same? yes no

and are "supplementary angles".

Define Supplementary Angles:

Construct a right angle ABC.

Construct a segment BD in the interior of the angle.

= =

What can you conclude about the sum of these two angles?

Move point D around the interior of the right angle, does your conclusion stay the same? yes no

and are "complementary angles".

Define Complementary Angles:

Return to Geometry Labs Home Page