Page 320 - ICSE Math 8

9. (a) {0, 1, 2, 3, 4, 5} (b) {3} (c) {1, 2, 3, ...} (d) {1, 2} 8. x = 3, QS = 20 units
10. (a) –2 (b) 2 11. (a) 4 (b) 4 9. (a) Rhombus, Square (b) Rectangle, Square
... Exercise 16.4
12. (a)
–1 0 1 2 3 4 5 6 7 1. ∠R = ∠A = 130° 2. 9 cm and 18 cm
... 4. x = 9, y = 5
(b)
–2 –1 0 1 2 5. (a) x = 50°, y = 90° (b) x = 70°, y = 130°
(c) Mental Maths
–2 –1 0 1 2
1. (a) (ii) (b) (i) (c) (iii) (d) (iv) (e) (i) (f) (ii)
(d)
0 1 2 3 4 2. (a) heptagon (b) perpendicular (c) triangle
(e) (d) rhombus (e) eight
–1 0 1 2 3 4
Practice Time
(f)
–6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 1. 58° 2. 5 cm 3. 68° 4. 37°, 143°, 37°, 143° 5. 90°
Think Smart 6. ∠SNO = 95°, ∠OPA = 95°, ∠SAN = 50°, ∠ANP = 10°
1. (d) 2. 48 3. (a) ≥ (b) ≥ (c) ≤ (d) ≥ (e) ≥ (f) ≤ 8. x = 50°, y = 50°, z = 50° 9. ∠F = 55°
4. 19 visits 10. 8 11. 20 m more 12. 60°

Chapter 16 Think Smart
1. (a) 3,108° (b) 4,120° (c) 6, 135° (d) 8,144°
Exercise 16.1 2. Two pieces each of 16 and 4 sq units, three pieces of
1. 72.5° each 2. 60°, 80°, 100°, 120° 8 sq units
3. (a) 120° (b) 80° (c) 75° 4. 60°
5. 64°, 80°, 96°, 120° 6. 80° each Chapter 17
7. x = 105° and y = 120° Mental Maths
1. (a) (ii) (b) (iii) (c) (i) (d) (ii) (e) (iii)
Exercise 16.2
1. 40°, 140°, 40°, 140° 2. 108°, 72°, 108°, 72° 2. (a) True (b) False (c) False (d) False (e) True
3. 18 cm 4. 110°, 70°, 110° Chapter 18
5. ∠S = 45°, ∠P = 135°, ∠U = 45° and ∠N = 135° Exercise 18.1
6. (a) Diagonals of parallelogram bisect each other. 1. (i) 8 vertices (ii) 5 faces (iii) 12 edges (iv) 20 faces
(b) Alternate interior angles are equal. (v) 5 vertices
(c) Vertically opposite angles are equal. 3. (a) A cylinder and cuboid (b) Two cones
7. 13 cm each 8. 60°, 120°, 60°, 120° (c) Half cylinder and cuboid (d) Cube and cone
9. (a) x = 70°, y = 110° (b) x = 10, y = 3 (e) Hemisphere and cylinder (f) Two cylinders
(c) x = 75°, y = 105° 10. 94°, 86°; 94°, 86° 4. (a) Square pyramid (b) Triangular prism
11. 20 m; 40 m (c) Regular tetrahedron (d) Octagonal prism
12. No, because diagonals of parallelogram bisect each other. (e) Hexagonal pyramid

Exercise 16.3 Exercise 18.2
1. (a) In a rectangle diagonals are equal. 1. (a) (i) Side (ii) Top (iii) Front
(b) ∆ COE ≅ ∆ AOP hence by CPCT. (b) (i) Front (ii) Top (iii) Side
(c) Diagonals are equal and bisect each other. (c) (i) Front (ii) Top (iii) Side
(d) Vertically opposite angles are equal. (d) (i) Top (ii) Front (iii) Side

2. cm 3. 5 cm each (e) (i) Front (ii) Side (iii) Top
4. KI = 12 cm, KE = 5 cm and ET = 12 cm 2. (a) — (iv) (b) — (i) (c) — (ii) (d) — (iii)
5. x = 130° 6. 20 cm and 25 cm Mental Maths
7. (a) Parallelogram (b) Rhombus, Square 1. (a) (i) (b) (ii) (c) (iv) (d) (iii) (e) (iv) (f) (i)
(c) Square, Rectangle 2. (a) (v) (b) (i) (c) (iv) (d) (ii) (e) (iii)

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