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### Vocabulary

Undefined Terms- point, line, and plane are considered undefined terms because they are only explained using examples and descriptions  Point- a location – it does not have shape or size (named by capital letter)  Line- made up of points and has no thickness or width (named by a lowercase letter, or two points on the line)  Plane- a flat surface made up of points that extends infinitely in all directions (named by a capital script letter, or 3 points in the plane) A P Q

m

J .

K .

L B .

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### Vocabulary

Collinear- points that lie on the same line  Coplanar- points that lie in the same plane  Intersection- the set of points that two or more geometric figures have in common  Space- a boundless, 3-D set of all points

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### Examples

Line g ; or line PN Line j; or line MT Plane S; or Plane TNQ

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### Practice

Line q Point B or Point A Line DC Plane G or Plane ABD

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### Examples

 4. Draw and label a figure for AK and CG intersect at point M in plane T. C

T

M K A G  5. How many planes are shown?

6

 6. Name 3 collinear points: SXM  7. Are points N, R, S, and W coplanar? Why (not)?

No. NRS all lie on plane A, but W is on plane WTQP

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### Practice

 4. Draw and label a figure for lines q and f intersect at point Z in plane U.

 5. How many planes are shown?

5

 6. How many of the planes contain points F and E?:

2

 7. Name 4 points that are coplanar: FEAB, or EDCB, or CAFD