Chapter 3.1: Identify Pairs of Lines and Angles
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Transcript Chapter 3.1: Identify Pairs of Lines and Angles
Chapter 3.1: Identify
Pairs of Lines and Angles
What angle pairs are formed by
transversals?
M11.B.2.1, M11.C.1.2
Parallel lines
◦ never intersect
◦ are coplanar
◦ The symbol for parallel lines is ||
◦ If line
l
l is parallel to line m you can represent it with
||
m.
◦ When 2 drawn lines are parallel there will be little arrows
or triangles on the lines.
Are these parallel judging by
sight?
Are these parallel?
Are these parallel?
Are these parallel?
Parallel planes are two planes that do not
intersect.
Parallel Planes
Perpendicular Planes are planes that
intersect at a 90˚ angle.
Perpendicular Planes
Skewed lines do not intersect, but are not
coplanar.
The last 2 examples were examples of
skewed lines.
Skewed Lines
Parallel Postulate
If there is a line and a point not on that
line, then you can draw only 1 line parallel
to the line that passes through that point.
Not parallel
.
Perpendicular Postulate
If there is a line and a point, then there is
one line that passes through the point
that is perpendicular to the line.
.
Not
Perpendicular
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# 3-10
Transversals
Transversals are lines that intersect two or
more coplanar lines at different points.
In other words a line that intersects 2
other lines.
transversal
There are 4 different angle
relationships created by a transversal
Corresponding angles: same side of
transversal and of the individual lines.
(angles 2 and 6)
Alternate interior: angles on the inside of
the 2 lines, but on either side of the
transversal. (angles 4 and 5)
Alternate exterior: angles on the outside
of the lines, but on opposite sides of the
transversal. (angles 1 and 8)
Consecutive interior: angles on the inside
of the lines and on the same side of the
transversal. (angles 3 and 5)
Identify Angles
1 5
2 6
3
4
7
8