Waec Mathematics 1999 Past Questions and Answers

Question 56:

• WAEC 1999

(a) Copy and complete the following table of values for \(y = 9 \cos x + 5 \sin x\) to one decimal place.

x	0°	30°	60°	90°	120°	150°	180°	210°
y		10.3			-0.2	-5.3		-10.3

(b) Using a scale of 2cm to 30° on the x- axis and 2 cm to 1 unit on the y- axis, draw the graph of \(y = 9 \cos x + 5 \sin x\) for \(0° \leq x \leq 210°\).
(c) Use your graph to solve the equation: (i) \(9\cos x + 5\sin x = 0\); (ii) \(9\cos x+ 5\sin x = 3.5\), correct to the nearest degree.
(d) Find the maximum value of y correct to one decimal place.