मान लीजिए $\theta_1$ और $\theta_2$ इस प्रकार हैं कि $(\theta_1-\theta_2)$,$3^{\text{rd}}$ या $4^{\text{th}}$ चतुर्थांश में स्थित है। यदि $\sin \theta_1+\sin \theta_2=-\frac{21}{65}$ और $\cos \theta_1+\cos \theta_2=-\frac{27}{65}$ है,तो $\cos \left(\frac{\theta_1-\theta_2}{2}\right)=$

  • A
    $\frac{3}{\sqrt{150}}$
  • B
    $\frac{3}{\sqrt{130}}$
  • C
    $-\frac{3}{\sqrt{130}}$
  • D
    $-\frac{3}{\sqrt{150}}$

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