Page 305 - Ganit Kaushal

(c) least angle of symmetry = 72°; angles of symmetry
= 72°, 144°, 216°, 288°, 360°; Order = 5.
4. P P H H L L T T (d) does not have more than one angles of symmetry.

3. Figure with seven arms. Not a whole number;
 3
the smallest angle of symmetry is 51 7 


S S V V X X degrees.
(Note: Students may think some other kind of figure)
4. (a) angles of symmetry = 120°, 240°, 360°; Order = 3.
The letters that have vertical line of symmetry will have (b) angles of symmetry = 90°, 180°, 270°, 360°;
same mirror images. These letters are H, T, V, X and Order = 4
hence these letters will look the same. While P, L and (c) angles of symmetry = 72°, 144°, 216°, 288°, 360°;
S do not look the same after reflection. Order = 5.

5. line of symmetry = 2; least angle of symmetry = 180°;
5. (b) (c) (d) angles of symmetry = 180°, 360°; Order = 2; 2-times.
6. 80°, 120°,160°, 200°, 240°, 280°, 320°, 360°
7. 30° 8. No.
Miscellaneous Exercise 9.3
(e) (f) 1. (b) 2. (a) 3. (d) 4. (a)
5. (d)
6. 6. (a) False (2LoS) (b) False (Infinite LoS)
(c) True (d) False (Only one) (e) False
7. (a) n (b) no (c) no (d) infinite

7. (a) no (b) no (c) yes (d) no (e) one
8. (a) False (1-LoS) 8. 120°, 180°, 240°, 300°, 360°.
(b) False (infinite lines of symmetry) 9. 20°, 40°, 60°; least angle of symmetry = 20°
(c) True 10. (a) yes (b) No,  23 is not a factor of 360.
11. 3, 4, 5, 6, 7, 8, 9, 10; counting numbers starting from 3.

(d) False ( Square has 4 and rectangle has 2 lines of 12. 24 lines of symmetry, least angle of symmetry = 15°;

symmetry) no. of angle of symmetry = 24
(e) False (8 lines of symmetry) (f) True 13. (a) 2; 180°, 360°; 180° (b) 2; 180°, 360°; 180°
9. (a) multiple (b) 4 (c) 3 (d) n (c) 6; 60°, 120°, 180°, 240°, 300°, 360°; 60°
(e) 4; H, I, O, X. (f) no 14. (a) S (0 line of symmetry)
10. (b) 11. (a) 12. (d) 13. (c) (b) M, A, T, C, E (1 line of symmetry)
14. (a) 15. (b) 16. (a) 17. (c) (c) H, I (2 lines of symmetry)
18. (b) 19. (b) 15. Yes, M 16. Z, N
Exercise 9.2
1. (a) angles of symmetry = 180°, 360°; 17. (a) (b) No line of symmetry
least angle of symmetry = 180°;
order = 2; Number of lines of
symmetry = 2(dotted) (a) (c) (d) No line of symmetry
(b) angles of symmetry = 180°, 360°; Assertion Reason Type Questions
least angle of symmetry = 180°;
order = 2; Number of lines of 1. (a) 2. (d) 3. (a) 4. (a)
symmetry = 2(dotted) (b) 5. (a) 6. (a) 7. (c) 8. (b)
2. (a) least angle of symmetry = 90°; angles of symmetry Chapter Test
= 90°, 180°, 270°, 360°; Order = 4. I. 1. (a) 2. (d) 3. (d) 4. (a)
(b) least angle of symmetry = 90°; angles of symmetry 5. (d) 6. (a) 7. (a) 8. (d)
= 90°, 180°, 270°, 360°; Order = 4. 9. (d) 10. (d) 11. (b)

Answers 303