Suzanne Chludzinski
schludzinski@hamden.org
ILS501-01
The Basic Elements of Geometry
Building Blocks of Geometry
•
Everything in Geometry is made of the
following three basic elements.
1. Point
2. Line
3. Plane
Point
•
•
•
•
Has no size
Only has location
Represented with a dot
Named with a capital letter
Point A
•A
Line
• Straight continuous arrangement of
infinitely many points
• Extends forever in two directions
• Represented by a line with arrows on each
end
• Named by giving any two points on the
line or a lower case letter.
•A
Line AB
•B
j
Line j
Plane
• Has length and width but no thickness
• Similar to a flat surface that extends
forever along its width and length
• Represented with a four sided figure and a
capital letter in the lower left corner.
• Named with a capital letter.
Plane P
P
Types of Lines
• Intersecting: lines that meet in one point.
– Perpendicular lines
• Non-intersecting: lines that never meet
– Parallel
– Skew
Perpendicular Lines
Definition: Lines that intersect at a 90
degree angle.
90 degrees
Examples of Perpendicular Lines
• Street Intersections
• Crosswalks
Parallel Lines
Definition: Lines that are in the
same plane that never intersect.
Examples of Parallel Lines
• Railroad Tracks
• Yellow Street Lines
Skew Lines
Definition: Lines that are in different planes
and never intersect