Section 3.6

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Perpendiculars and Distance
Key Concepts:
The distance from a line to a point not on the line is the length of the segment perpendicular to the line from the point.

The distance between 2 parallel lines is the distance between one of the lines and any point on the other line.

2 lines in a plane are parallel if they are everywhere equidistant. Equidistant means that the distance between two lines measured along a perpendicular line to the lines is always the same. The distance between parallel lines is the length of the perpendicular segment with endpoints that lie on each of the 2 lines.

Theorem 3.9- In a plane, if two lines are equidistant from a third line, then the two lines are parallel to each other.