Download Week of Feb. 19

Geometry
Vocabulary
Introduction to
Classifying Angles
Line
• a straight path that connects two
points, but extends past both
points, forever.
• to identify a line, select two
points, and draw the symbol of a
line over it. A line ALWAYS has
arrows at both ends.
AB
Segment
• two points and all the points in a
straight path between them
• to identify a segment, select two
endpoints, and draw the symbol
of a segment over it. A segment
DOES NOT have arrows at the
ends.
EF
Ray
• an endpoint and all the points in a
straight path in one direction
• to identify a ray, start with an
endpoint, then use another point
in the direction you want. For
example, point G going to point B
would be:
GB
Vertex
• the common endpoint of an
angle.
• (also, a corner point of a
geometric figure)
How do you recognize a vertex?
Angle
• two rays with a common
endpoint.
How do you name an angle?
Right Angle
• an angle that measures
exactly 90°
How do you identify a right
angle?
Acute Angle
• an angle that measures
less than 90°
What does it look like?
Straight Angle
• an angle that measures
exactly 180°
What does it look like?
Obtuse Angle
• an angle that measures
more than 90°, AND less
than 180°
What two angles is an obtuse
angle between?
Adjacent Angles
• two angles that share a
common vertex, and one
side, but have no common
interior points.
How would you draw
adjacent angles?
Vertical Angles
• when 2 lines intersect, they
form 4 angles. The angles
across from each other are
called, ‘vertical angles.’
What do vertical angles look
like?
Complementary Angles
• the sum of their measures
equals 90°
What kind of angle do
complementary angles form?
Supplementary Angles
• the sum of their measures
equals 180°
What kind of angle do
supplementary angles form?
Triangles
& more vocabulary
Triangle
• a polygon with three sides.
• The sum of the 3 angles
equals exactly 180°.
Congruent
• being exactly equal in size
and shape.
What can be congruent?
sides
angles
polygon
Scalene Triangle
• has NO congruent sides.
Isosceles Triangle
• has at least TWO congruent
sides.
Equilateral Triangle
• has THREE congruent sides.
• Question: If the three sides
are congruent, what do you
think each angle measure will
be?
60°
Right Triangle
• a triangle with a right angle
If one angle is 90°, what must be
the sum of the other two
angles?
Acute Triangle
• a triangle with ALL three
angles being acute angles.
Obtuse Triangle
• A triangle with one obtuse
angle.
If a triangle is obtuse, what
type of angles must the
other two angles be?