Download Geo_Lesson 3_1 Notes

Geometry – Lesson 3.1 (Lines and Angles)
0. Activity: Lines in Space
Will AD and CG ever intersect in space? Why?
Do these pairs of lines intersect?
(a) BC and AE?
(b) GH and DH?
(c) CD and DH?
1. Parallel Lines
Two lines are __________________ lines if they lie in the same plane
and do not intersect.
The symbol for parallel is ________.
Lines _____ and _____ are parallel.
2. Perpendicular Lines
Two lines are ______________________ lines if they intersect to
form right angles.
The symbol for perpendicular is _____.
Lines _____ and _____ are perpendicular.
3. Skew Lines
Two lines are ___________ lines if they do _______ lie in the
same plane and do ______ intersect.
Lines _____ and _____ are skew lines.
4. Parallel Planes
Two planes are ________________ lines if they do not intersect.
Planes _____ and _____ are parallel planes.
Example 1:
(d) AB and DH?
Practice 1: Parallel, skew, or perpendicular?
5. Parallel / Perpendicular Postulates
Parallel Postulate: If there is a line (l) and a point not on the line
P
Line l
(P), then there is __________ ________ ______________ line
through the point.
Perpendicular Postulate: If there is a line (l) and a point not on
the line (P), then there is _____________ ________
P
Line l
________________ _______ line through the point.
6. Angles Formed by Transversals (VERY IMPORTANT!!!)
A ___________________ is a line that interse cts two or more
coplanar lines at different points.
7. Alternate Interior / Exterior Angles
Alternate interior angles: Lie on
Alternate exterior angles: Lie on
________________ sides of the transversal
________________ sides of the transversal
_______________ the two lines.
_______________ the two lines.
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8. Corresponding / Consecutive Interior Angles
Corresponding angles: Occupy
Consecutive interior angles: Lie on the
_______________________ positions.
___________ side of the transversal
____________________ the two lines.
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Example 2a/b: List all pairs of:
Alternate exterior s
Corresponding s
Consecutive interior s
Alternate interior s
Vertical s
Linear pair s
Practice 2
9. Closure
If you have a line and a point. How many parallel lines go through the point?
How many perpendicular lines?
What’s the difference between alternate interior and alternate exterior angles?