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# Undefined Terms and Definitions - PowerPoint PPT Presentation

Undefined Terms and Definitions. Undefined Terms. Point simply a location represented by a dot named with a capital letter no shape no size. Undefined Terms (cont.). Line made up of points no thickness or width drawn with an arrowhead at each end

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Undefined Terms and Definitions

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## Undefined Terms and Definitions

### Undefined Terms

Point

• simply a location

• represented by a dot

• named with a capital letter

• no shape

• no size

### Undefined Terms (cont.)

Line

• no thickness or width

• drawn with an arrowhead at each end

• named by the letters representing two points on the line or by a lowercase script letter

• has symbol in label above two letters

SL or LS

### Undefined Terms (cont.)

Plane

• flat surface made up of points

• no depth

• extends infinitely in all directions

• drawn as a shaded, slanted four-sided figure

• named by a capital script letter or by the letters naming three points in the plane that are not on the same line

### Definitions (cont.)

Collinear - points on the same line

Coplanar - points that lie on the same plane

Intersection – The point(s) in common among figures

Space – A boundless three-dimensional set of all points.Space can contain lines and planes.

Locus – A set of points that all satisfy a particular condition.

Use the figure to name each of the following.

a. a line containing point X

b. a plane containing point Z

### Example 1-1d

Answer:plane P, plane XYZ, plane ZYX, plane YZX, plane XZY, plane ZXY, plane YXZ

VISUALIZATION Name the geometric shape modeled by each object.

a. a colored dot on a map used to mark the location of a city

b. the ceiling of your classroom

### Example 1-4e

a. How many planes appear in this figure?

### Example 1-4f

b. Name three points that are collinear.

### Example 1-4g

c. Are points X, O, and R coplanar? Explain.

Answer: Points X, O, and R all lie in plane T, so they are coplanar.

d. At what point do and intersect?