3.1 Lines and Angles3.1 Lines and AnglesRelationships between linesRelationships between lines

Identify angles formed by a Identify angles formed by a transversal transversal

Lines that do not touch

Parallel lines are coplanar lines that do not intersect

Skew lines are noncoplanar lines that do not intersect.

Parallel line are shown with arrows in the line as well as the end

Parallel planes

The floor and the ceiling are parallel planes.

Hopefully they will not touch

Postulate 13 (can be proven with an indirect proof)

If there is a line and a point not on the line, then there is exactly one line through the point parallel to the given line.

Postulate 13 (can be proven with an indirect proof)

If there is a line and a point not on the line, then there is exactly one line through the point parallel to the given line.

Postulate 14

If there is a line and a point not on the line, then there is exactly one line through the point perpendicular to the given line.

Postulate 14

If there is a line and a point not on the line, then there is exactly one line through the point perpendicular to the given line.

Transversal line

A transversal line is a line that cuts through 2 or more coplanar lines.

1 2

3 4

5 6

7 8

Transversal line

A transversal line makes groups of angles.

Corresponding Angles

1 2

3 4

5 6

7 8

84

73

62

51

and

and

and

and

Transversal line

A transversal line makes groups of angles.

Alternate Exterior Angles

1 2

3 4

5 6

7 8 72

81

and

and

Transversal line

A transversal line makes groups of angles.

Same Side Interior Angles

1 2

3 4

5 6

7 8

64

53

and

and

HomeworkHomework

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