MATHEMATICS

1. Circle MATHEMATICS

2. S Q Chord PQ P Diameter DE D E O Centre Radius OM F M Arc RE G Circle in daily life Circle in music Circle in sports Circle Centre Circumference Circular region Radius Diameter Chord Arc Semicircle Segments of a circle Crossword Contents

3. CIRCLE IN DAILY LIFE A circle BACK

4. Many musical instruments have a circular surface. For example: Tabla Bingo Drum Bass Drum Snare Drum CIRCLE IN MUSIC BACK

5. CIRCLE IN SPORTS A circle Five rings in the logo of Olympic games BACK

6. What is a Circle? Acircleis a closed curve in a plane. A circle can be drawn with the help of a circular object. For example: A circle drawn with the help of a coin. BACK

7. Circle and Centre of a circle A circle is a closed curve consisting of all points in a plane which are at the same distance (equidistant) from a fixed point inside it. A circle O Centre This fixed point (equidistant) inside a circle is called centre. A circle has one and only one centre. BACK

8. Circumference A Centre A circle O The distance around a circle is called its circumference. BACK

9. Centre O 1. The circle Circular Region A circle divides a plane into three parts. 3. Exterior of a circle 2. Interior of a circle A plane The interior of a circle together with its circumference is called the circular region. BACK

10. O Centre Radius Radius M A point on the circle A line segment that joins any point on the circleto its centreis called a radius. (Contd…)

11. (Contd…) N Centre O M Radius K L • Radii ( plural of radius) of a circle are equal in length. • Infinite number of radius can be drawn in a circle. BACK

12. O Centre Diameter A A circle Diameter AB B A line segment that joins any two points on the circle and passes through its centre is called a diameter. (Contd…)

13. (Contd…) Centre M A A circle P O Q B N • Infinite number of diameters can be drawn in a circle. • As the radii of a circle are equal in length, its diameters too are equal in length.

14. (Contd…) Diameter MN N M O Radius ON Radius OM Centre Radius OM = Radius ON Diameter MN = Radius OM + Radius ON The length of the diameter of a circle is twice the length of its radius. BACK

15. Chord B is another point on the circle A is a point on the circle A B A line segment that joins point A and B Chord O A line segment that joins any two points on the circle is called a chord.

16. M Chord MN N O D C Chord CD Diameter CD K Chord KL L Diameter is also a chord of the circle. (Contd…)

17. M N Chord MN O C D Diameter CD K L Chord KL D C M N The diameter is the longest chord. (Contd…)

18. O Centre M N Chord MN G Chord GH K L Chord KL H Infinite number of chords can be drawn in a circle. BACK

19. K L O Centre Arc Arc An arc is the distance between any two points on the circumference of a circle. (Contd…)

20. X K L O Centre Naming an arc Arc KXL An arc is named by three points, of which two are the end points of the arc and the third one lies in between them. (Contd…)

21. K L Minor Arc KXL O Centre Major Arc KYL Y X An arc divides the circle into two parts: the smaller arc is called the minor arc, the larger one is called the major arc. (Contd…)

22. Example of an arc An arc An arc BACK

23. Arc DSE Arc DRE Semicircle DSE Semicircle DRE Semicircle S Diameter E D O Centre R • Half of a circle is called asemicircle. • A semicircle is also an arc of the circle. (Contd…)

24. Semicircle DSE O Centre Semicircle DRE Semicircular region Diameter E D Semicircular region Thediameterof a circle divides it into 2 semicircular regions. BACK

25. Segments of a Circle S Minor segment of a circle E D Chord DE Centre O Major segment of a circle R A chord divides the circular region into 2 parts, each of which is called a segment of the circle. (Contd…)

26. Minor arc DPE Centre O Major arc DQE P E D Minor segment of the circle Chord DE Major segment of the circle Q • The part of the circular region enclosed by a minor arc and the chord is called a minor segment. • The part of the circular region enclosed by a major arc and the chord is called a major segment. • Minor segment does not contain the centre of the circle. • Major segment contains the centre of the circle. BACK

27. Recap the Terms O Centre Radius Diameter Chord Arc Semi Circle

28. O Centre Radius OM M Radius Diameter Chord Arc Semi Circle

29. Diameter DE E D O Centre Radius Diameter Chord Arc Semi Circle

30. Q Chord PQ P O Centre Radius Diameter Chord Arc Semi Circle

31. Arc PQR E O Centre F G Radius Diameter Chord Arc Semi Circle

32. Semicircle DSE S Semicircle Diameter E D O Centre Semicircle Radius Diameter Chord Arc Semi circle

33. Circle Crossword

34. C 2 Across: 4. The line segment that joins any two points on the circle and passes through its centre. 5. A closed curve in a plane. 6. All points on the circle are equidistant from this point. 7. A line segment that joins any two points on a circle. 1 A 4 D M I A E T E R 3 R A R 5 C D I C R L E U I M U F S E Down 1. The distance between any two points on the circumference of the circle. 2. The distance around the circle. 3. The distance from the centre of the circle to a point on the circle. R E C 6 E T N E N 7 C H R D O E

35. The End