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5 (c) Appears much more than a (b) (i)
8. (a) x , –
6 right angle.
(b) –5 < x , 8 Thus, estimated size is
(c) x < –1 about 130°. 72° 78°
Let’s Practise 4. (a) 52° 30° 78°
(b) 115°
1. (a) , (b) , (c) .
(c) 146°
2. (a) x . 18 72 + 30° + 78° = 180°
(b) x + 3 . 21 Self Practice 8.1c (ii)
(c) x – 5 . 13 1. (a) Reflex angle
3. 20 – 1.20x . 5 (b) The angle on a straight line 78°
4. (a) 170 + n (c) The angle of one whole turn 72°
(b) 1, 2, 3, 4, 5, 6, 7 2. (a) (i) 30° 78°
5. (a) x , 4 (b) x , 2 135°
45°
6. 14 g
88°
7. 17 hours
8. (a) 15n + 200 . 290 78°
(b) 7 135° + 45° = 180° 72° 78°
9. RM751 (ii) 30°
10. (a) – 4 < x < 3 135°
8 45°
(b) x . 88°
3
(c) 3 < x < 7 78°
5 72°
(d) < x , 3 78°
2 30°
Chapter 8 Lines and Angles 135°
45°
88°
Self Practice 8.1a
1. (a) Congruent; PQ = RS 78°
(b) Not congruent; PQ ≠ RS 72° 78°
(c) Congruent; PQ = RS 135° 30°
45°
2. (a) Congruent; ∠PQR = ∠ABC 88°
(b) Not congruent;
∠PQR ≠ ∠ABC
(c) Congruent; ∠PQR = ∠ABC 78°
135° 72°
Self Practice 8.1b
45° 30° 78°
1. (a) 4 cm. Use a 4 cm long 88°
eraser.
(b) 6 cm. Use a 3 cm long A reflex angle is more
paper clip. A reflex angle is more than 180° and less than
(or other objects of known lengths) than 180° and less than 360°.
360°. (iii)
2. (a) 4.3 cm
(b) 5.8 cm (iii)
3. (a) Appears slightly more than 135° 72° 78°
a right angle. 88° 45° 78°
Thus, estimated size is 30°
about 100°.
(b) Appears slightly less than a The angle of one whole The angle of one whole
right angle. turn is 360°. turn is 360°.
Thus, estimated size is
about 80°.

316
Answers

14 Ans Math F1.indd 316 11/10/16 12:23 PM