Chapter 3.1: Identify Pairs of Lines and Angles

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Chapter 3.1 Identify Pairs of Lines and Angles
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M11.B.2.1, M11.C.1.2

• What angle pairs are formed by transversals?

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• Parallel lines
• never intersect
• are coplanar
• The symbol for parallel lines is
• If line l is parallel to line m you can represent
  it with l m .
• When 2 drawn lines are parallel there will be
  little arrows or triangles on the lines.

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Are these parallel judging by sight?
R
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Are these parallel?
S
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Are these parallel?
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Are these parallel?
y
z
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Parallel Planes

• Parallel planes are two planes that do not
  intersect.

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Perpendicular Planes

• Perpendicular Planes are planes that intersect at
  a 90 angle.

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Skewed Lines

• Skewed lines do not intersect, but are not
  coplanar.
• The last 2 examples were examples of skewed lines.

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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.

.
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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.

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• Page 150
• 3-10

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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
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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)

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• 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)

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Identify Angles