Chapter 1 Flashcards
Line
Has one dimension
Extends infinitely in two directions
Point
Has no dimension, just a place in space
Represented as a dot
Named with a capital letter
Plane
Has two dimensions
Extends infinitely in all directions
Represented with a wall or floor like shape
Named by using any 3 points in the plane or script uppercase
Collinear
Points on the same line
Any two points are collinear
A line can be drawn through them
To see that 3 points are collinear there has to be a line drawn through them
Because it is not possible to draw a line through any 3 points but it is possible for 2 points.
Coplanar
Points on the same plane
Any three points are coplanar
A plane can be drawn through them
If there is more than 3 points there must be a plane drawn through them
Line Segment
Has two endpoints
Named using the two endpoints
Ray
Has one endpoint, goes on forever in one direction
Named using one endpoint and one point on the line
Opposite Rays
2 rays that share an endpoint, forming a line
Intersection
When 2 or more figures share a line or point
Lines intersect at a point
Planes intersect at a line
Planes go forever in one direction so the lines have to go forever in one direction
Segment Addition Postulate
If B is between A and C then AB+BC=AC
The parts of a segment add up to a segment
Congruent Segments
Segments with the same length
Midpoint
The point that divides the line segment into congruent parts
Segment Bisector
A point, line, ray, segment or plane that that crosses a segment through its midpoint.
Midpoint Formula
Average the 2 numbers to find the midpoint for 2 points on a number line
Angle
Created when 2 rays have the same endpoint; the amount of rotation from on ray to another
Vertex
The point where 2 rays meet; the “middle point”
Sides
The two rays making up the angle
Acute angle
Between 0 and 90 degrees
Right Angle
90 degrees
Obtuse Angle
Between 90 and 180 degrees
Straight Angle
180 degrees
Angle Addition Postulate
Adding the smaller angles to get the bigger angle
Angle Bisector
A ray that divides an angle into 2 congruent angles
Adjacent Angles
Two angles that share a vertex and side, but no point
Complimentary Angles
Two angles that add up to 90 degrees
Supplementary Angles
Two angles that add up to 180 degrees
Linear Pair
Two angles that are adjacent and supplementary (form a straight line)
Vertical angles
Two angles whose sides make straight lines, but only cross at the vertex
Polygon
A closed plane figure
The vertices, where the lines connect, have only 2 sides
Concave polygon
When sides are extended, at least one enters the polygons
Convex Polygon
When sides extended and none enters the shape
Equilateral
Polygons with congruent sides
Equiangular
Polygons with congruent angles
Regular
All sides and angles congruent
