What you’ll learn
Define segments and rays.
Key idea
Segment lengths are positive distances; when B is between A and C, adjacent lengths add.
Segment length is absolute distance; reversing ray labels changes endpoint and direction.
Worked example
Enter the exact value or ordered values in the format requested below.
Number line coordinates A=-4, B=-9, C=-11; B lies between A and C and C is beyond B on ray AB. Find segment BC length.
- AB=|-9-(-4)|=5; AC=7.
- BC=AC-AB=7-5=2; ray AB starts at A and extends left, whereas ray BA starts at B in the opposite direction.
Answer: 2
Quick Check
Evaluate a worked attempt at define segments and rays, identify the first invalid step, and provide the correction.
Number line coordinates A=-4, B=1, C=3; B lies between A and C and C is beyond B on ray AB. Student: Step 1, AB length is 5. Step 2, ray AB and ray BA are the same set of points. Identify the first invalid step and repair.