Advanced Trigonometry, SMB-034 Find every angle, \(\theta\), between \(-180^{\circ} \leq \theta \leq 180^{\circ}\), for which \(\cos\,\theta=\dfrac{\sqrt{3}}{2}\) (2 marks) --- 5 WORK AREA LINES (style=lined) --- Show Answers Only \(\theta=30^{\circ}, -30^{\circ}\) Show Worked Solution \(\text{Reference angle:}\ \ \cos\,\theta=\dfrac{\sqrt{3}}{2}\ \ \Rightarrow \ \ \theta = 30^{\circ}\) \(\text{cos is positive in 1st/4th quadrants.}\) \(\theta=30^{\circ}, (360-30)^{\circ}=30^{\circ}, 330^{\circ}\) \(\therefore \theta=30^{\circ}, -30^{\circ}\ \ \ (-180^{\circ} \leq \theta \leq 180^{\circ}) \)