Page 315 - ICSE Math 7

Exercise 19.3 4. (a) Circle (b) Circle (c) Circle (d) Square
1. Three different isometric sketches are 5. (a) 24 cubes (b) 9 cubes

Mental Maths
1. (a) (ii) (b) (iii) (c) (i) (d) (iv) (e) (i)
(a) (b)
2. (a) True (b) False (c) True (d) False (e) False
3. (a) polygons; triangles (b) edge (c) vertex
(d) prism (e) sphere (f) tetrahedron (g) 30
Practice Time
1. (a) and (c)
(c)

2. (a) (b)

2.

3. (a) 46 (b) 29 (c) 17

Oblique sketch Isometric sketch (d) 1 (e)

4. (a) (iii) ; (b) (iv) ; (c) (i) ; (d) (v) ; (e) (ii)
3. (a) (b)
Think Smart
1. F + V = E + 2, F = faces, V = vertices, E= edges of a
polyhedron
For an icosahedron, number of edges (n) = F + V – 2 =
20 + 12 – 2 = 30
2. Top view
4. (a) (b)

Side view
Front view
Chapter 20
5. Mental Maths
1. (a) (ii) (b) (iv) (c) (iii) (d) (iii) (e) (iii) (f) (iii)
2. (a) False (b) False (c) True (d) True (e) True
Exercise 19.4 3. (a) greater (b) 100° (c) exterior
Figure (1) (2) (3) Chapter 21
1.
(a) Front (or top) Side Top (or front) Exercise 21.1
2
(b) Top Side Front 1. (a) 40 cm; 96 cm (b) 70 m; 300 m 2
2
2
(c) Front (or side) Side (or front) Top 2. (a) 64 cm (b) 13.52 cm 3. ` 36,000
4. 25 cm, 82 cm
(d) Top Side Front
2
5. (a) 62 cm, 122 cm (b) 60 cm, 72 cm 2
6. (a) ` 94,710 (b) 10 rounds
2
2
2. (d) 3. 7. 80 m 8. 30 cm 9. (a) 1,820 m (b) 4,480 m 2
10. ` 5,100; ` 9,424
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