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Straight line, ray, segment
Textbook: Part 3, lesson 73, pp. 4–5
GoalTell a straight line, a ray and a segment apart.
New words
straight line · to‘g‘ri chiziqray · nursegment · kesmapoint · nuqta
Explanation
A straight line goes on forever in both directions, so it has no ends. A ray starts at a point and goes on in one direction. A segment has a point at both ends, so we can measure its length. Through two points we can draw only one straight line.
Worked examples
AB is a straight line, CD is a ray (it starts at point C), EF is a segment (it has ends E and F).
A tightly pulled string looks like a segment, and a beam of a torch looks like a ray.
Class activity
“Draw with a string”: two children hold the ends of a string – a segment. A third child pulls from one end and says “A ray!” Children then draw a segment, a ray and a straight line in their notebooks.
Practice
1
How many straight lines can be drawn through one point?
As many as you like
2
How many straight lines can be drawn through two points?
1
3
Which line has a point at both ends: straight line, ray or segment?
Segment
4
Points A, B, C lie on one line, with B between A and C. Segment AB is 9 cm and BC is 6 cm. How many cm is AC?
15
5
An artist worked 3 days: 2 h 40 min, 2 h 25 min and 2 h 20 min. How many minutes in total?
445