Download Alternate Interior Angles

Geometry 3.1
Big Idea: Identify
pairs of lines and
angles
Vocabulary
Parallel Lines:
Two lines that do not intersect
and are coplanar.
Skew Lines:
Two lines that do not intersect
and are not coplanar.
Parallel Planes:
Two planes that do not
intersect.
Ex: plane RSTU || plane WXYZ
Note: a small triangle (like an arrow,
pointed in one direction of a line) is
used to indicate that lines are
parallel (our book uses red color to
denote this) – the arrow is on each
line, not at the end
Postulates
Postulate 13:Parallel Postulate
If there is a line and a point not on
the line, then there is exactly one
line through the point ║ to the
given line.
P
m
Postulate 14:Perpendicular Lines
If there is a line and a point not
on the line, then there is exactly
one line through the point ┴ to
the given line.
P
m
More Vocabulary
Transversal:
A line that intersects 2 or more
coplanar lines at different points.
Corresponding Angles: on same
side of transversal with same
relationship (on top or on bottom)
to other 2 lines (2 & 6), others?
Alternate Interior Angles:
Angles that lie between the 2 lines on opposite
sides of the transversal (3 & 5), others?
Alternate Exterior Angles:
Angles that lie outside the 2 lines on
opposite sides of the transversal.
(2 & 8), others?
Consecutive Interior Angles:
Angles that lie between the 2 lines on the
same side of the transversal.(4 & 5 ),others?
Example: Identify all pairs of
angles of the given type.
• Corresponding
• Alternate Interior
2
1
3
4
6
5
7
• Alternate Exterior
8
• Consecutive interior
• Vertical