If `costheta=(cosalpha-cosbeta)/(1-cosalpha.cosbeta)` , prove that `t a ntheta/2=+-tan(alpha/2)cot(beta/2)` .

Explanation

To prove that \( \tan \frac{\theta}{2} = \pm \tan \frac{\alpha}{2} \cot \frac{\beta}{2} \) given that

\[ \cos \theta = \frac{\cos \alpha - \cos \beta}{1 - \cos \alpha \cos \beta}, \]

we will follow these steps:

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