1. GEOMETRY H2 (HOLT 1-1B) K.SANTOS UNDERSTANDING POINTS, LINES, AND PLANES (POSTULATES)

2. POSTULATE (AXIOM) Statement accepted as truth without proof Cannot prove why it is true Usually seems “obvious” Must memorize the rules Sometimes they are numbered (referenced back to a book) Never name postulate by it’s number (can use name if it has one)

3. POSTULATE 1-1-1 Through any two points there is exactly one line AB

4. POSTULATE 1-1-2 Through any three noncollinear points there is exactly one plane containing them. N M O

5. POSTULATE 1-1-3 If two points lie in a plane, then the line containing those points lies in the plane.

6. POSTULATE 1-1-4 If two lines intersect, then they intersect in exactly one point A

7. POSTULATE 1-1-5 If two planes intersect, then they intersect in exactly one line.