1. ABC, ABD and DBC
2. a. Acute b. Reflex c. Acute d. Right e. Obtuse f. Straight
3. a. (i) 80o (ii) 130o (iii) 57o
b. (i) 60o (ii) 30o (iii) 89o
4.
a
|
b =120o | (Vert. opp. s equal) |
b
|
d = 128o | ( Adj. s on st. line add up to 180°) |
c
|
m = 83o | (s at a pt. add to 360°) |
d
|
r = 58o |
(Vert. opp. s equal) |
e
|
y = 40o |
(Vert. opp. s equal) ( Adj. s on st. line add up to 180°) (Vert. opp. s equal) |
f
|
p = 32o n = 35o |
( Adj. s on st. line add up to 180°) ( Adj. s on st. line add up to 180°) |
Some answers can be arrived at in different ways.