Page 291 - ICSE Math 6

4. (a) and (c) Chapter 15
5. (a) m and n (b) l and m; l and n (c) l and m; l and n Exercise 15.1
6. (a) infinite (b) open (c) indefinite (d) closed; three 1. (a) P and S (b) R and Q (c) A, B, T and C
(e) equal (f) 90° (g) radius 2. Acute angles; 5°, 65°; Obtuse angles: 96°, 170°;
7. (a) Tip of a pen, tip of a pin Reflex angles: 190°, 320°
(b) Edges of a paper, edges of a table 3. ∠CAB and ∠DAB
(c) Light rays coming from electric blue, rays coming 4. (a) True (b) False (c) False (d) True
from sun
(d) Surface of a wall, surface of a notebook 5. Angle ∠AOB ∠AOC ∠BOC ∠COD ∠DOA ∠DOB
Classification Obtuse Straight Acute Right Right Reflex
(Answers may vary)
6. Complementary angles: (a) and (f); supplementary angles:
8. (a) (b) (c) (b) and (d); Congruent angles: (c) and (e)
A B A B A B
9. (a) and (b) 7. Vertically opposite angles: ∠AOC and ∠BOD, ∠AOD
and ∠BOC;
Exercise 14.2 Adjacent angles: ∠AOC and ∠AOD, ∠AOC and ∠BOC,
1. (a) True (b) False (c) True (d) True (e) False ∠BOD and ∠AOD, ∠BOD and ∠BOC;
2. Concurrent lines 3. (a) Infinite (b) Infinite (c) One Linear pairs: ∠AOC and ∠AOD, ∠AOC and ∠BOC,
4. (a) (Answers may vary) ∠BOD and ∠AOD, ∠BOD and ∠BOC
A B P
8. (a) 2 (b) 2 (c) 2 9. 11 10. 90°
P
(b) (Answers may vary) Exercise 15.2
A B
1. 9.3 cm 2. AB < CD
(c)
A P B 3. Students to do on their own.
5. (a) A, B, D (b) A, B, C or B, C, D or A, C, D (c) A 4. (a) 56° 9′ 35″ (b) 161° 13′ 28″ (c) 20° 6′ 40″
(d) 60° 34′ 50″
Mental Maths 5. 233° 20′ 43″ 6. (a) 22° (b) 60° (c) 122° (d) 130°
1. (a) length; breadth (b) two (c) one; initial (e) 310° (f) 200°
(d) parallel (e) two 7. Students to do on their own.
2. (a) False (b) True (c) True (d) False 3. (a) and (b) Mental Maths

Practice Time 1. (a) False (b) True (c) False (d) False
1. (a) 7 (b) 8 (c) 13 2. (a) exterior (b) 60 (c) 60 (d) 360° (e) inner; outer
2. (a) p and n (b) p and l; n and l; m and l (c) m and l Practice Time

A A A 1. (a) 242° 16′ 1″ (b) 81° 56″ (c) 101° 23′ 32″
3. (a) (b) (c) (d) 262° 45′ 50″
B B 2. (a) 8° (b) 75° (c) 115° (d) 120° (e) 330° (f) 250°
B
4. (a) and (d) 5. Yes 6. Yes 7. Ring, CDs 3. Students to do on their own.
A 4. (a) ∠DOE, ∠COE (b) ∠BOE (c) ∠AOE
A B E 5. 14 right angles 6. 10 right angles 7. No
8. (a) (b) B
D C D 8. (a) Straight (180°) (b) Right (90°)
C (c) Complete (360°) (d) Reflex (270°)
9. No 10. CO and OD 11. CD 9. 7° 43' 5'' 10. Ladder B

12. (a) D, O, A, B (b) OC (Answers may vary) (c) BD Think Smart
(d) OD, OA, AB, OC, DA (Answers may vary) 1. (iv) 2. (ii) 3. 4 right angles
13. Samir, as he is in the interior of region. 4. 45° each 5. 145° 6. 162°
14. Carpenter B
Chapter 16
Think Smart Exercise
1. (ii) 2. (iii) 3. (a) 10 (b) 20 4. Yes 5. parallel

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