1. ~Adapted from Walch Education
Defining Terms
~Adapted from Walch Education

2. A point is not something with dimension.
A point is an exact position or location in a given plane.
In the coordinate plane, these locations are referred to with an ordered pair (x, y),
A line requires two points to be defined. A line is the set of points between two reference points and the infinite number of points that continue beyond those two points in either direction. A line is infinite, without beginning or end. This is shown in the diagram below with the use of arrows. The symbol is used to represent line AB.

3. a ray is defined by two points; however, a ray has only one endpoint
a ray is defined by two points; however, a ray has only one endpoint. The symbol is used to represent ray AB.
Similarly, a line segment is also defined by two points, but both of those points are endpoints. A line segment can be measured because it has two endpoints and finite length. Line segments are used to form geometric figures. The symbol is used to represent line segment AB.

4. An angle is formed where two line segments or rays share an endpoint, or where a line intersects with another line, ray, or line segment. The difference in direction of the parts is called the angle. Angles can be measured in degrees or radians. The symbol is used to represent angle A. A represents the vertex of the angle. Sometimes it is necessary to use three letters to avoid confusion. In the diagram below, can be used to represent the same angle, Notice that A is the vertex of the angle and it will always be listed in between the points on the angle’s rays.

5. An acute angle measures less than 90° but greater than 0°
An acute angle measures less than 90° but greater than 0°. An obtuse angle measures greater than 90° but less than 180°. A right angle measures exactly 90°.
Two relationships between lines that will help us define transformations are parallel and perpendicular. Parallel lines are two lines that have unique points and never cross. If parallel lines share one point, then they will share every point; in other words, a line is parallel to itself.

6. Perpendicular lines meet at a right angle (90°), creating four right angles.

7. A circle is the set of points on a plane at a certain distance, or radius, from a single point, the center. Notice that a radius is a line segment. Therefore, if we draw any two radii of a circle, we create an angle where the two radii share a common endpoint, the center of the circle.

8. Creating an angle inside a circle allows us to define a circular arc, the set of points along the circle between the endpoints of the radii that are not shared. The arc length, or distance along a circular arc, is dependent on the length of the radius and the angle that creates the arc—the greater the radius or angle, the longer the arc.

9. Thanks for Watching!!!
~ Ms. Dambreville