\

SPM Additional Mathematics 2019, Paper 2 (Question 6)


Question 6:
Solution by scale drawing is not accepted.
Diagram 3 shows the positions of jetty O and kelongs K, L, R, S and T in the sea.

Diagram 3

Kelong
L is situated 400 m from jetty O and kelong R is situated 600 m from jetty O in the direction of OL. Kelong S is situated 300 m from jetty O and kelong T is situated 600 m from kelong 5 in the directions of OS. Kelongs L, K and T are situated on a straight line such that the distance of kelong K from kelong T is 5 times its distance from kelong L.

(a) By using to represent 100 m in the direction of OR and  to represent 150 m in the direction of OT, express in terms of p˜ and q˜.
[3 marks]
(i) OK,        (ii) RK.

(b) If Joe uses a binocular to observe kelong
R from kelong S, determine whether kelong R can be seen without being blocked by kelong K or otherwise.
Prove you answer mathematically.     [5 marks]


Solution:
(a)
KT=5KLKTKL=51KT:KL=5:1OL=4p˜, LR=2p˜, OR=6p˜OS=2q˜, ST=4q˜, OT=6q˜


(a)(i)
OK=OL+LK     =4p˜+16LT     =4p˜+16(4p˜+6q˜)     =4p˜23p˜+q˜     =103p˜+q˜

(a)(ii)
RK=RO+OK     =6p˜+103p˜+q˜     =83p˜+q˜

(b)
SR=OROS     =6p˜2q˜     =2(3p˜q˜)KR=RK     =(83p˜+q˜)     =83p˜q˜SRmKR,m is a constant.
S
, K and R are not collinear.
Hence, Kelong R can be seen without being blocked by Kelong K.

Leave a Comment