Warm Up-9/18/07 (#4) Find the value of a.
a-20
4a
Homework Answers… 1. E, EL, EA 2. ∠ADL, ∠EDT 3. ∠DLT 4. ∠LAT 5. ∠AEL 6. ∠2 7. ∠7 8. ∠6 9. ACUTE 10. ACUTE 11. RIGHT 12. ACUTE 13. STRAIGHT 14. OBTUSE
15. LAS 16. 1 17. LE bisects ∠ALS 18. 180 26. A. 90, 90, 90 26. B. 87, 93, 87 29. 18 31. 9 33. 20
1.5 Postulates and Theorems
Objective- Recognize postulates and theorems related to points, lines, and planes.
Postulate A line contains at least two points; a plane contains at least three points not all in one line; space contains at least four points not all in one plane.
Postulate Through any two points there is exactly one ____. LINE “Exactly one” means one and only one.
Postulate Through any three points, there is at least one ____, and through any three noncollinear points there exactly one ____. PLANE PLANE Tripod Postulate
Postulate If two points are in a plane, then the line that contains the points is in that plane.
Postulate If two planes intersect, then their intersection is a ___. LINE
Theorem A statement that is proved! Recall: Postulate
Theorem If two lines intersect, then they intersect in exactly one ______. POINT
Theorem Through a line and a point not in the line, there is exactly one ______. PLANE
Theorem If two lines intersect, then exactly one ______ contains the lines. PLANE
HOMEWORK>>> Page 25; 3-11 and 13-16