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Question 3

(a) In a right angled triangle, sin x = 3/5. Evaluate 5(cos x)³  3.
(b) The angle of elevation of the top of a vertical pole from a point 63m east of the base of
the pole is 30°. From another point due west of the pole, the angle of elevation of the
top is 60°
(i)Draw a sketch diagram to illustrate the information.
(ii)Calculate, correct to three significant figures, the distance of the second point
from the base of the pole.

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Part (a) of this question was well attempted by majority of the candidates. They were able to
apply the Pythagoras theorem correctly to find the length of the third side of the triangle = 4
and cos x as 4/5,Substituting this value of cos x in the given expression and simplifying gave the
final answer as 1/5
In part (b), the report stated that majority of the candidates could not interpret the question
correctly which showed poor understanding of the topic. They were unable to draw the diagram
correctly and this also affected their being able to answer the question correctly. Teachers are
encouraged to emphasize the need for diagrams during instruction.
From the diagram, /TB/ = xtan 60° = 63tan 30°• This implied that x =63tan30 = 21.0 m
tan 60



