Page 347 - Start Up Mathematics_7

Solve Mentally
True or False

1. True 2. False 3. False 4. True 5. False
(c) (d)
6. True 7. False 8. True
Fill in the Blanks
1. anticlockwise 2. translation 3. 8
Exercise 13.2 4. 1 5. 120° 6. 60° 7. point 8. line
1. (a) order 2 (b) order 2 (c) No rotational symmetry Answer in One Word or a Line
(d) order 4 (e) order 4 (f) order 2 (g) order 2
1. 4 2. 90° 3. Rotational symmetry
(h) order 3 (i) No rotational symmetry (j) order 4
4. 2, its diagonals
(k) No rotational symmetry
5. Rotation turns an object about a fixed point called centre
Letters Line Number Rotational Order of of rotation.
symmetry of lines of symmetry rotational
2. Yes/No symmetry Yes/No symmetry 6. 180° 7. No
H Yes 2 Yes 2 Let’s Evaluate
E Yes 1 No 1 1. Badminton racket, cricket bat, coin and a tube light

C Yes 1 No 1 2. Figure Lines of Angle of
symmetry rotational
N No 0 Yes 2 symmetry
Z No 0 Yes 2 (a) 4 90°
S No 0 Yes 2 (b) 2 180°
(c) 0 180°
(d) 4 90°
3. (a), (c), (d), (e) (e) 6 60°
(f) 4 90°
4. (a) (b) (c) (g) 1 360°
equilateral isosceles parallelogram (c)
triangle triangle 3. (b) ✕ ✕ ✓ ✓ ✕ ✓ ✕ ✓
(d) ✓ ✕ ✕ ✕ (e) ✕ ✕ ✕ ✓
(d) (e) (f) ✓ ✕ ✕ ✓
isosceles scalene
trapezium triangle Thinking Skills
1. Only line symmetry: A, B, C;

Only rotational symmetry: N, S, Z
5. (a) (b) (c) 2. Yes, two or more lines of symmetry implies rotational
isosceles rhombus square
trapezium symmetry. For example letters H, I, O have 2 lines of
6. For 45° rotation—90°, 135°, 180°, 225°, 270°, 315° and symmetry hence rotational symmetry as well. No for
360° example a parallelogram has rotational symmetry but no
An angle of rotation of 50° is not possible. line symmetry.
For 60° rotation—120°, 180°, 240°, 300° and 360° 3. (a) rotation (b) rotation (c) reflection (d) rotation
7. (a) Yes (b) Yes (c) Yes (d) No (e) Yes (f) No 4. (a) 90° (b) 180° (c) 90° (d) 270°
Review Exercises 5. (a) 5, 72° (b) 2, 180° (c) 6, 60° (d) 4, 90°
Multiple Choice Questions (e) 12, 30° (f) 3, 120°

1. d 2. b 3. c 4. d 5. c
6. (a) Yes (b) Yes (c) Yes (d) No
6. d 7. b 8. c 9. d 10. d
(e) No (f) Yes

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