(a) Copy and complete the table of values for \(y = 3\sin x + 2\cos x\) for \(0° \leq x \leq 360°\). x 0° 60° 120° 180° 240° 300° 360° y 2.00 2.00 (b) Using...

Assessment: WAEC SSCE - General Mathematics - 2008 (Essay) Subject: General Mathematics

Question 1 Report

(a) Copy and complete the table of values for \(y = 3\sin x + 2\cos x\) for \(0° \leq x \leq 360°\).

x 0° 60° 120° 180° 240° 300° 360°
y 2.00 2.00

(b) Using a scale of 2 cm to 60° on x- axis and 2 cm to 1 unit on the y- axis, draw the graph of \(y = 3 \sin x + 2 \cos x\) for \(0° \leq x \leq 360°\).

(c) Use your graph to solve the equation : \(3 \sin x + 2 \cos x = 1.5\).

(d) Find the range of values of x for which \(3\sin x + 2\cos x < -1\).

Answer Details

(a) For \(y=3\sin x+2\cos x\), the completed table is:

\(x\)\(0^\circ\)\(60^\circ\)\(120^\circ\)\(180^\circ\)\(240^\circ\)\(300^\circ\)\(360^\circ\)
\(y\)2.003.601.60-2.00-3.60-1.602.00

For example, at \(x=60^\circ\), \(y=3(0.8660)+2(0.5)=3.598\approx3.60\).

(b) The graph, drawn using the stated scales, is shown below.

graph
Smooth curve of y = 3 sin x + 2 cos x for 0° ≤ x ≤ 360°. The horizontal reference lines are y = 1.5 and y = -1.

(c) Draw the horizontal line \(y=1.5\). Its intersections with the curve give

\[x\approx122^\circ\quad\text{or}\quad x\approx351^\circ.\]

(d) Draw the horizontal line \(y=-1\). The curve is below this line between its two points of intersection. Hence,

\[\boxed{162^\circ<x<310^\circ}.\]

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