Error: The points should be subtracted. Correct Solution: AB=3.5
Practice makes perfect
When measuring the length of a segment, we use the Ruler Postulate. The first step is to take the difference between the end points of the segment. This is the error in the exercise, they are adding the points instead of subtracting them.
1 + 4.5 &= 5.5 && *
1 - 4.5 &= -3.5 && ✓
When we subtract the points, we will get a negative result. That's why we need to take the absolute value — a length can never be negative. The correct way to calculate the length of the segment is:
AB=|1-4.5|=3.5
