Year 4-Points, Lines, Line Segments, Rays and Angles.pptx

chapter 5 lines and angles

1. Points, Lines, Line Segments, Rays and Angles Saturday, 26 October 2013 1 Maths Year 4 By: Jinky Dabon

2. Saturday, 26 October 2013 2 A point is a location. A point has no size. We use a dot to mark a point. We use a letter to name a point. For example, when A is used to name a point, it is shown as ·A and read as Point A .

3. Saturday, 26 October 2013 3 A line is a straight path that goes on forever in both directions. A line has no width. Lines The arrows show that the line goes on forever.

4. Saturday, 26 October 2013 4 The line is called ‘ line AB ’ or ‘ line BA ’. The symbol for ‘ line AB ’ is written as AB . The symbol for ‘ line BA ’ is written as BA . Point A and Point B are two points on the line. A B

5. Saturday, 26 October 2013 5 (a) E F Exercise. Write the name and symbol for each line. (b) Y Z (c) O P

6. Saturday, 26 October 2013 6 Draw and name the line represented by each symbol. (a) CD (b) GH (c) WX (d) JK

7. Saturday, 26 October 2013 7 A line segment is a part of a line with two end points. Line SEGMENTS line segment end points

8. Saturday, 26 October 2013 8 The name of the line segment is ‘ line segment AB ’ or ‘ line segment BA ’. The symbol for ‘ line segment AB ’ is written as AB . Point A and Point B are the end points of a line segment. A B The symbol for ‘ line segment BA ’ is written as BA .

9. Saturday, 26 October 2013 9 How many line segments are there? Name them. H F G E A B C D E Draw a picture that has 8 line segments, name them and write the symbols for all the line segments.

10. Saturday, 26 October 2013 10 A ray is a line with one end point and an arrow at the other end. RAY ray end point The arrow shows that the line goes on forever from here.

11. Saturday, 26 October 2013 11 The name of the ray is ‘ ray AB ’. Point A is the end point. The symbol for ‘ ray AB ’ is written as AB . There is an arrow after Point B . A B

12. Saturday, 26 October 2013 12 S R The first letter in the name of a ray must be the letter at the end point. The arrowhead in the symbol must always point to the right. So, to write RS is wrong. It should be written as RS . From the symbol RS , we know that the point R is the end point.

13. Saturday, 26 October 2013 13 How would you name these rays? U V S T Write the name and symbol of each ray. D C J K Draw and name the ray represented by each symbol. (a) TS (b) BC (c) LM

14. Saturday, 26 October 2013 14 Intersecting points An intersecting point is the point where two lines, line segments or rays intersect or cross each other. D E F G H Point H is the intersecting point DE and FG intersect at Point H .

15. Saturday, 26 October 2013 15 R S T U Point T is the intersecting point RS and TU intersect at Point T .

16. Saturday, 26 October 2013 16 Name the intersecting points. U V W S V U T R J H I F G

17. Saturday, 26 October 2013 17 ANGLES Two rays or two lines segments with a common end point forms an angle . The two rays or line segments are called the sides of the angle. The common end point is called the vertex of the angle.

18. Saturday, 26 October 2013 18 O P Q PO and PQ are two rays that form an angle . The common end point is Point P . So, Point P is the vertex of the angle. The angle is named ‘ angle OPQ ’ or ‘ angle QPO ’ . The symbol for ‘ angle OPQ ’ is written as OPQ . The symbol for ‘ angle QPO ’ is written as QPO .

19. Saturday, 26 October 2013 19 THE END