1. Points, Lines, and Planes
Lesson 1
Points, Lines, and Planes

2. 3 undefined terms in geometry
Point – location with no size
Line – a straight path that has no thickness and extends forever in opposite directions
Plane – a flat surface that has no thickness and extends forever
point B, point C, etc.
𝐴𝐵 , 𝐵𝐷 , 𝐶𝐵 , line n
plane ADC, plane P, but not plane DAB
WHY?

3. Collinear and Noncollinear points
Any set of 3 or more points that lie on the same line are called collinear points In the diagram, points D, E, and G are collinear Points that do not lie on the same line are noncollinear Points F, D, and E are noncollinear

4. Identifying lines
List all possible names for 𝐷𝐺 𝐺𝐷 𝐷𝐸 𝐸𝐷 𝐸𝐺 𝐺𝐸
line p

5. Coplanar and Noncoplanar
Lines or points that are in the same plane are coplanar
intersecting & parallel lines
set of 4 or more points, 3 of the points are noncollinear
Lines or points that are not in the same plane are noncoplanar
Are points A, B and D coplanar?
Yes, because any 3 noncollinear points will determine a plane, even if the plane is not “drawn”.
Collinear/noncollinear – 3 pts
Coplanar/noncoplanar – 4 pts

6. Identify Coplanar & Noncoplanar
What are 2 names for this plane
plane ACG, plane J
Name 2 coplanar lines
line i and line h
Name noncoplanar points
points E, A, G, B
Name 2 noncoplanar lines
𝐹𝐾 & 𝐴𝐵

7. Intersection is the point or set of points in which 2 figures meet
What is the intersection of :
𝐴𝐵 & 𝑀𝑁
point G
plane L & plane K 𝑀𝑁
plane K & 𝐸𝐹
point B

8. Questions/Review
The use of symbols with upper and lower case letters are important in the naming of geometric figures Do you like it when your name is misspelled? So please take note and use them appropriately 𝑀𝑁
All have different meanings
What do you think they are?