Arithmetic Grade Five

Lesson One hundred seventy-three: Line Length

When talking about length in this lesson we won't worry about the units involved.

On the grid to the left there are four line segments:

  1. red (-4,1) to (-4,7)
  2. yellow (3,2) to (7,2)
  3. purple (8,-2) to (8,-9)
  4. cyan (-8,-2) to (-2,-2)
You can figure out the length of each segment as long as you know the coordinates of its end points.

For vertical line segments the length is the difference between the two y-coordinates;

The vertical line segments are the purple and the red ones.

LENGTH OF PURPLE LINE SEGMENT: -2 - -9 = 7

LENGTH OF RED LINE SEGMENT: 7 - 1 = 6

The horizontal line segments are the cyan and yellow ones.

LENGTH of CYAN LINE SEGMENT: -2 - -8 = 6

LENGTH OF YELLOW LINE SEGMENT: 7 - 3 = 4

When calculating the length of a line segment always subtract the smaller value from the larger value.

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