help with maths paper 4!!

[soccerprinc3]

hii i'd appreciate it if anyone could help me out with a question i'm not understanding at all!

http://www.xtremepapers.me/CIE/Cambridg ... _qp_41.pdf

questions 9. (a) (iv), (v), (vi)
(b) (iii)
(c)

Thanks in advance