waecmaths question:
If $\cos \theta =x$and $\sin {{60}^{\circ }}=x+0.5$ ${{0}^{\circ }}<\theta <{{90}^{\circ }}$find correct to the nearest degree, the value of θ
Option A:
66o
Option B:
67o
Option C:
68o
Option D:
69o
waecmaths solution:
$\begin{align} & \sin {{60}^{\circ }}=x+0.5 \\ & 0.8660=x+0.5 \\ & x=0.8660-0.5 \\ & x=0.3660 \\ & \cos \theta =0.3660 \\ & \theta ={{\cos }^{-1}}(0.3660)\approx {{69}^{\circ }}\text{ to the nearest degree} \\\end{align}$
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