Step 1 :\( \sin^2(\theta) + \cos^2(\theta) = 1 \)
Step 2 :\( \cos^2(\theta) = 1 - \sin^2(\theta) \)
Step 3 :\( \cos^2(\theta) = 1 - \left(\frac{7}{25}\right)^2 \)
Step 4 :\( \cos^2(\theta) = 1 - \frac{49}{625} \)
Step 5 :\( \cos^2(\theta) = \frac{625}{625} - \frac{49}{625} \)
Step 6 :\( \cos^2(\theta) = \frac{576}{625} \)
Step 7 :\( \cos(\theta) = \pm \frac{24}{25} \)
Step 8 :\( \cos(\theta) = -\frac{24}{25} \) (\text{since } \theta \text{ is in Quadrant II})
Step 9 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{1 - \cos(\theta)}{2}} \)
Step 10 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{1 - \left(-\frac{24}{25}\right)}{2}} \)
Step 11 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{1 + \frac{24}{25}}{2}} \)
Step 12 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{25}{25} + \frac{24}{25}} \)
Step 13 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{49}{25}} \)
Step 14 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{49}{25} \cdot \frac{2}{2}} \)
Step 15 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{98}{50}} \)
Step 16 :\( \sin \left(\frac{\theta}{2}\right) = \pm \sqrt{\frac{49}{25}} \)
Step 17 :\( \sin \left(\frac{\theta}{2}\right) = \pm \frac{7}{5} \sqrt{\frac{1}{2}} \)
Step 18 :\( \sin \left(\frac{\theta}{2}\right) = \pm \frac{7}{5} \cdot \frac{\sqrt{2}}{2} \)
Step 19 :\( \sin \left(\frac{\theta}{2}\right) = \pm \frac{7\sqrt{2}}{10} \)
Step 20 :\( \sin \left(\frac{\theta}{2}\right) = \frac{7\sqrt{2}}{10} \) (\text{since } \frac{\theta}{2} \text{ will be in Quadrant I})
Step 21 :\(\boxed{\sin \left(\frac{\theta}{2}\right) = \frac{7\sqrt{2}}{10}}\)