1.4 intersections in geometry, figures intersect if they have any points in common. the intersection...
TRANSCRIPT
1.4 Intersections
• In geometry, figures intersect if they have any points in common.
• The intersection of two or more figures is the point or points that the figure have in common.
A
s
t
Postulate 3
Postulate 3: Intersection of Two Lines
If two lines intersect, then their intersection is a point.
P
s
t
Postulate 4
• Postulate 4: Intersection of Two Planes
• If two planes intersect, then their intersection is a line.
Visualize it!
• Two lines can intersect even if the diagram does not show where they intersect. The lines below intersect at a point that is not shown.
m
n
Example 1
• Use the diagram at the right.• a. Name the intersection
of AC and BE.
• b. Name the intersection of BE and DF.
• c. Name the intersection of AC and DF.
A B
ED
C
F
Example 2
• Use the diagram at the right.
• a. Name the intersection of planes S and R.
• b. Name the intersection of planes R and T.
• c. Name the intersections of planes T and S.
S
R
T
k
l
Checkpoint
• Use the diagram at the right.
• 1. Name the intersection of PS and QR.
• 2. Name the intersection of TV and QU.
• 3. Name the intersection of PS and UV.
P
Q
SR
TU V
Checkpoint
• Use the diagram at the right.
• Name the intersection of planes Q and L.
• Name the intersection of planes Q and Z.
• Name the intersection of planes Z and L.