1-1 Points, Lines, and Planes.
definition: known words to describe a new word
In geometry there are three undefined terms: point, line and
plane. We must be in agreement about what each is.
Partner Activity.
Point
Line
Plane
Collinear
Coplanar
Segment
Ray
Opposite Rays
Intersection:
What is the intersection of 2 lines?
What is the intersection of 2 planes?
Postulate
Postulates:
1. Through any 2 pts. there is exactly one line.
2. Through any 3 noncollinear pts. there is exactly one plane
containing them.
3. If 2 pts. lie in a plane, then the line containing those pts. also
lies in the plane.
4. If 2 lines intersect, then they intersect in exactly one pt.
5. If 2 planes intersect, then they intersect in exactly one line.
Draw and label the following:
3. a segment with endpoints M and N.
4. opposite rays with common endpoint, T.
5. 2 lines intersecting in exactly 1 pt.