1. 1.4 Intersections 1.5 Segments
Basics of Geometry
1.4 Intersections
1.5 Segments

2. POINT LINE PLANE LINE Review
The intersection of two lines is a ___________.
The intersection of two planes is a ________.
Any three points can define a ___________.
Any two points can define a ________.
POINT
LINE
PLANE
LINE

3. Review B C D A E F G H Name 4 coplanar points.
Are A, D, and E coplanar?
Are A, D, G, and F coplanar?
Are E and F collinear?
Give plane ADC another name.

4. Intersections of Lines
Name the intersection of and A B C D E F

5. Intersections of Planes
Name the intersection of planes S and R.
Name the intersection of planes R and T.
Name the intersection of planes T and S. S R k T l

6. Sketch It! P Sketch and label a plane.j P
Sketch and label a plane.
Draw and label a line that is in the plane.
Draw and label a line that does not intersect the plane.
Draw and label a line that intersects the plane at one point.

7. Sketch It!
Sketch and label two planes that intersect. S R k

8. p. 11: 8, 14, 24, 36, 38 p. 17: 16 – 32 even Assignment :
First, we will discuss page 17.
Then, quietly work on your own work. I will help if you need it.
p. 11: 8, 14, 24, 36, 38
p. 17: 16 – 32 even

9. Segments A segment is a part of a line. A segment has a length.
To find the length of a segment (or the distance from beginning to end), subtract the coordinates of the endpoints and take the absolute value.

10. Segments Continued
The notation for distance is simply the endpoints of the segment.
Thus, the formula for distance on a line segment is:

11. Find AB A B -5 13

12. Segment Addition PostulateB C
If B is between A and C, then AC = AB + BC
If AC = AB + BC, then B is between A and C

13. Find EF 16 D E F 10

14. Find AB 29 C A B 15

15. Find DF D E F 12 7

16. Congruency Shapes that have the same dimensions are called congruent.
Two segments who have the same length are called congruent.
The symbol for congruency is

17. Congruent Segments B A D C
Congruent segments are often marked with a short tick mark. A B C D

18. Congruent Segments
Sometimes multiple tick marks will be used. R S H T

19. Assignment
Pages 31 – 33
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