Point
A position in space represented by a dot and a capital letter (Point A...etc.) .
Line
A straight section of space running infinitely in two directions, represented by one or more points on it (Line AB...etc.) and arrows reaching out <----.---.--->
Line segment
A part of a line bounded by two endpoints, with a measurable length, named by its endpoints (Line segment AB...etc.) .____.
Plane
An infinitely expanding area of space that is flat and often represented by bounded figures; the whole plane is often given a name (Plane A...etc.) /\ /\ < --I------------I--> I I < --I------------I--> V V
Collinear
Points that are contained in a single line.<----.A--.B--->
Noncollinear
Points that are not contained in a single line.<----.A---.B--->.C
Coplanar
Points that are contained in a single plane._________| .A .C I|_____.B__I
Concurrent
Lines that cross at a single line. /\ | < -- .--> | V
Ray
A part of a line that extends infinitely in one direction; to name a ray, we name the endpoint first (Ray AB)..A-----.B-->
Angle
A pair of rays that have the same endpoint, and can be named in multiple ways (Line A, Line AB, Line ABC, Line 1... etc.) /\ / .A / / 1.B-------.C-->
Sides
The rays of an angle are considered these.
Vertex
The shared endpoint of an angle is called this.
Protractor
An instrument used to measure angles by degrees from 0- 180.
Polygon
A figure bounded line segments and contained in a plane. [] |> <>
Polyhedron
A figure bounded by polygons and existing through space, 3-D.
Triangle, quadrilateral, pentagon, hexagon, octagon
3 sides, 4 sides, 5 sides, 6 sides, 8 sides<I [] /------| \____|
Perimeter
The distance around a polygon, measured by the sum of the lengths of its sides.
Area
The amount contained inside of a polygon, measured for a rectangle as the length times the width (A= lw).