Introduction to Geometry

Created by

Jereny Sebastian

Cards (19)

Point 
Image: dot [ ᐧ ]
How to name: ᐧP (read as point P)
It has no length, width or thickness and occupies no space
Line 
Image:
How to name: line l or
Has infinite length but has no width and thickness and it is straight
Naming lines with multiple points 
Line m
WX
XY
WY
Plane 
Image:
How to name: Plane P or Plane ABC
Has infinite length and width, but no thickness and it is a flat surface
Other terms 
SPACE - set of all points
FIGURE - any set of points
COPLANAR - set of points that lie on the same plane
COLLINEAR - points that lie on the same line
NON-COLLINEAR - points that do not lie on the same line
NON-COPLANAR - points that do not lie on the same plane
A, B and D are collinear
A, B and C are non-collinear
A, B, C and D are coplanar
Points that do not lie on the plane are non-coplanar
Intersecting lines 
Two lines that meet at a common point
Perpendicular lines 
Two lines are perpendicular if they intersect and form right angles
Symbol for perpendicular: ⟂
Parallel lines 
Coplanar lines that do not meet
Symbol for parallel: //
Concurrent lines 
Three or more lines that have a common point
Parallel planes 
Planes that have no common points
Skew lines 
Two lines that are not coplanar
Intersecting planes 
Planes that intersect on a line
Segment 
It is a part of a line
A segment has two endpoints
Ray 
It is another part of a line
It has one endpoint and a part that is continuously extending
Angle 
It is formed by two non-collinear rays that have a common endpoint
The endpoint is the vertex of the angle
Each ray is the side of the angle
Naming angles 
∠B
∠ABC
∠𝜃
Acute angle 
An angle whose measure is greater than 0 but less than 90
Right angle 
An angle whose measure is exactly 90
Obtuse angle 
An angle whose measure is greater than 90 but less than 180