If $630^{\circ} < \theta < 810^{\circ}$ and $\tan \theta=-\frac{7}{24}$, then $\cos \left(\frac{\theta}{4}\right)=$

• Correct answer
  A

  $-\sqrt{\frac{7+5 \sqrt{2}}{10 \sqrt{2}}}$
• B

  $\sqrt{\frac{7+5 \sqrt{2}}{2 \sqrt{2}}}$
• C

  $-\sqrt{\frac{5 \sqrt{2}-7}{10 \sqrt{2}}}$
• D

  $\sqrt{\frac{5 \sqrt{2}-7}{2 \sqrt{2}}}$

Hence, the correct answer is option: 'A'.