Advanced Trigonometry, SMB-033 Find every angle, \(\theta\), between \(0^{\circ} \leq \theta \leq 360^{\circ}\), for which \(\cos\,\theta=-\dfrac{1}{\sqrt{2}}\) (2 marks) --- 5 WORK AREA LINES (style=lined) --- Show Answers Only \(\theta=135^{\circ}, 225^{\circ}\) Show Worked Solution \(\text{Reference angle:}\ \ \cos\,\theta=\dfrac{1}{\sqrt{2}}\ \ \Rightarrow \ \ \theta = 45^{\circ}\) \(\text{cos is negative in 2nd/3rd quadrants.}\) \(\theta=(180-45)^{\circ}, (180+45)^{\circ}=135^{\circ}, 225^{\circ}\)