QUESTION 4
-
(a). If sin x =
, where 0o ≤ x ≤ 90o, without using tables or calculator, calculate
.
(b).
In the diagram, ∠PQT = 200o, ∠TQR = 32o and ∠QRS = x. Find the value of x.
Observation
The Chief Examiner reported that majority of the candidates who attempted this question performed well in part (a) but poorly in part (b). In part (a), candidates were reported to apply the basic concept of trigonometry correctly. They were able to obtain the values of cos x = 
and tan x = 
. Substituting these values into the expression gave 
= 
= 2
or 2.58.
In part (b), candidates were expected to show that ∠PQR = 360o – (200 + 32)o = 128o (angle at a point). This implied that ∠QRS = 180o – 128o = 52o (adjacent angles on a transversal). Hence, x = 360o – 52o = 308o (angle at a point).