ધારો કે $\theta_1$ અને $\theta_2$ એવા છે કે જેથી $(\theta_1-\theta_2)$ એ $3^{\text{rd}}$ અથવા $4^{\text{th}}$ ચરણમાં આવે છે. જો $\sin \theta_1+\sin \theta_2=-\frac{21}{65}$ અને $\cos \theta_1+\cos \theta_2=-\frac{27}{65}$ હોય,તો $\cos \left(\frac{\theta_1-\theta_2}{2}\right)=$

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

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