1. Basics of Geometry Defining Terms
A point has no dimension.
It is usually represented by a small dot. A
Point •

2. A line extends without end in two directions
A line extends without end in two directions. It is usually represented by a straight line with two arrowheads to indicate that the line .

3. .
A plane extends in two
dimensions. It is usually
represented by a shape that
looks like a table or a wall,
however you must imagine
that the plane extends without end

5. The ray AB (symbolized by ) ) consists
of the initial point A and all points on AB
that lie on the same side of A as point B.
The first letter must indicate the starting point of the ray.

7. If C is between A and B, then CA and CB are opposite rays.
Like points, segments and rays are collinear if they lie
on the same plane. So, any two opposite rays are
collinear. Segments, rays, and lines are coplanar if they lie on the same plane.

8. Consider the line AB (symbolized by AB).
The line segment or segment AB
(symbolized by AB) consists of the
endpoints A and B, and all points on AB
that are between A and B.

9. Angle two rays with a common initial point.
the rays are called the sides of the angle.
the common initial point is called the vertex.
vertex
sides

10. Classifying Angles Acute Angles
Angles with a measure between 0o and 90o. A

11. Classifying Angles Acute Angles Right Angles
Angles with a measure between 0o and 90o.
Right Angles
Angles with a measure of exactly 90o. A

12. Classifying Angles Acute Angles Right Angles Obtuse Angles
Angles with a measure between 0o and 90o.
Right Angles
Angles with a measure of exactly 90o.
Obtuse Angles
Angles with a measure between 90o and 180o. A

13. Classifying Angles Acute Angles Right Angles Obtuse Angles
Angles with a measure between 0o and 90o.
Right Angles
Angles with a measure of exactly 90o.
Obtuse Angles
Angles with a measure between 90o and 180o.
Straight Angles
Angles with a measure of exactly 180o. A

14. Collinear Points
points that lie on the same line

15. Non-collinear Points
points that do not lie on the same line D A B

16. Coplanar points are points that lie on the same plane.B
Plane M or plane ABC

17. Perpendicular Lines are two lines that intersect to form a right angle.

18. Equidistant is having the same distance from a point or a line.

19. Equidistant from Two Points
P is equidistant
from Q and S Q S
Equidistant from Two Points
A point that has the same measure
to each of two other points.

20. Points P and Q are equidistant from line m.
the distance
from P to line m
the distance
from Q to line m
is PM Q
is QR m P R
Points P and Q are equidistant from line m. M
Distance from a Point to a Line
The length of a perpendicular segment
from the point to the line.

21. Congruent Figures
Two geometric figures are congruent if they have exactly the same size and shape

22. Similar Figures
Two geometric figures are similar if the corresponding angles are congruent and corresponding sides are proportional.