For this question, I will be writing 'csc' instead of 'cosec'
[tex]4\sin x-\csc x=\cot x\\\\4\sin x-\frac{1}{\sin x}=\frac{\cos x}{\sin x}\\\\4\sin^{2} x-1=\cos x\\\\4(1-\cos^{2} x)-1=\cos x\\\\4-4\cos^{2} x-1-\cos x=0\\\\4\cos^{2} x+\cos x-3=0\\\\ (4\cos x-3)(\cos x+1)=0\\\\\cos x=\frac{3}{4}, 1\\\\\therefore \boxed{\cos^{-1} \left(\frac{3}{4} \right), 180^{\circ}, 360^{\circ}-\cos^{-1} \left(\frac{3}{4} \right)}[/tex]
