topic 9 vocabulary
TRANSCRIPT
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 1/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Important Terms:
Point: A definite location in space.
Line: A series of points that goes forever in both directions.Plane: an infinitely large 2 dimensional (flat) surface.
Points and lines "rest" on a plane. A solid shape, like a
cube has multiple planes. Each face of the cube is its own
plane.
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 2/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Important Terms: Digging Deeper with Lines
Line Segment: Part of a line, has endpoints
Ray: Part of a line that has one endpoint, other end
continues forever in one direction.
Angle: 2 rays or line segments that meet at a common
point.
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 3/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Important Terms: Digging Deeper with Lines
Parallel Lines: 2 lines that never intersect
Intersecting Lines: 2 lines that cross paths
Perpendicular lines: 2 lines that intersect at a right angle (90º)
Note: The terms parallel, intersecting and perpendicular can
be used with rays and line segments.
Square Symbol is frequently used to show a right angle
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 4/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Important Terms: Digging Deeper with Angles
Acute Angle: An angle that measures less than 90º
(0º < Acute Angle < 90º)
Right Angle: An angle that measures exactly 90º
(Think corner of a square)
Obtuse Angle: An angle that is greater than 90º
(90º < Obtuse Angle < 180º)
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 5/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Important Terms: Creating Shapes with Angles and Line Segments
Polygon: A closed figure (shape) that only has line segments for
sides.
Triangle: A 3-sided polygon
Quadrilateral: a 4-sided polygon
Pentagon: a 5-sided polygon
Hexagon: a 6-sided polygon
Octagon: an 8-sided polygon
Polygons Not Polygons
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 6/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Focus on Triangles:
Triangles are named by their angle types and side lengths
Angle Naming Side Naming
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 7/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Focus on Triangles:
Triangles are named by their angle types and side lengths
The best way to name a triangle is with both the angle name and side
name:
Acute Isosceles Obtuse Scalene Right Isoceles
all acute angles 1 obtuse angle 1 right angle
2 equal sides 0 equal sides 2 equal sides
Special Case!
An Equilateral Triangle is a triangle with 3 equal sides. You don't need to
call it an "Acute Equliateral", it's just an Equilateral.
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 8/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Focus on Quadrilaterals
Quadrilaterals are 4-sided polygons
Quadrilaterals are classified or named by how their sides relate to each other.
We need to use the most specific name.
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 9/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
Focus on Quadrilaterals
The sequence below might help to show why when we name a quadrilateral we need to
use the most specific name.
yes
yes
yes
yes
YES! .... and the most specific name
8/8/2019 Topic 9 Vocabulary
http://slidepdf.com/reader/full/topic-9-vocabulary 10/10
January 18, 20
Topic 9: Lines, Shapes and Angles (2D Geometry)
One last thing to remember. Really knowing what all the
terms on the previous pages are only part of what we need
to be able to do as learners.
So, while it is important that we know what a line segment is
or what a trapezoid is, we will also be working a great deal
on how to apply the knowledge of these geometrical terms.