1. Points, Lines, and Planes
Sections 1.1 & 1.2

2. Notecard 1 Definition of a Point A point has no dimension.
It is represented by a dot.
A point is symbolized using an upper-case letter.

3. Notecard 2 Definition: Line
A line has one dimension. (infinite length)
A line is named using any two points on the line with a two sided arrow above them like this: 𝐴𝐵 . It can also be named by using a lower-case cursive letter.
Through any two points, there is exactly one line.

4. Notecard 3 Definition: Collinear points
points that lie on the same line.

5. Notecard 4 Definition: Between
If a point is between two other points then that means it must also be collinear with the other two points.

6. Notecard 5 Definition: Plane
A plane has two dimensions. It is represented by a shape that looks like a floor or a wall, but it extends infinitely in length and width.
Any three non-collinear points can define a plane.
A plane is named using the word plane with 3 non-collinear points or with an upper-case cursive letter.

7. Notecard 6 Definition: Coplanar:
Coplanar points are points that lie (or could lie) in the same plane.

8. Notecard 7 Definition: Line Segment:
The line segment consists of two endpoints and all the points between them.
A line segment is named using both endpoints with a line above them like this: 𝐴𝐵 .
𝐴𝐵 and 𝐵𝐴 refer to the same line segment.

9. Notecard 8 Definition: Ray
The ray consists of an endpoint and all points on a line in the opposite direction.
A ray is named using its endpoint first and then any other point on the ray with a ray symbol pointing to the right above them like this: 𝐴𝐵 .
𝐴𝐵 and 𝐵𝐴 do not refer to the same ray.

10. Notecard 9 Definition: Opposite Rays:
If point C lies on line AB between A and B, then ray CA and ray CB are opposite rays.
Two opposite rays make a line.

11. Notecard 10 Definition: Intersection:
The intersection of two or more figures is the set of points the figures have in common.
The intersection of 2 different lines is a point.
The intersection of 2 different planes is a line.

12. Notecard 11 Definition: Distance:
The distance between points A and B, also known as the length of line segment AB is the absolute value of the difference of the coordinates of A and B. In other words, distance is many units apart the points lie.
The distance from A to B, or the length of 𝐴𝐵
Is written as AB. (No symbol above).

13. Notecard 12
Definitions: Postulate: A rule that is accepted without proof. Theorem: A rule that can be proven.

14. Notecard 13 The Ruler Postulate:
The points on a line can be matched one to one with the real numbers.

15. Notecard 14 Segment Addition Postulate:
If B is between A and C, then AB + BC = AC.
If AB + BC = AC, then B is between A and C.

16. Notecard 15 Definition: Congruent Segments:
Line segments that equal (=) length are called congruent (≅)segments.
To show that two segments are congruent in a drawing we use tick marks.
A B C D