Trigonometric Ratios And Identities

If $540^{\circ}<\theta<630^{\circ}$ and $\tan \theta=5 / 12$, then

\(\frac{\cos \frac{\theta}{2}-5 \sin \frac{\theta}{2}}{\sqrt{-(12 \sec \theta+5 \operatorname{cosec} \theta)}}=\)