Question

solve it quickly please answer fast

Answer 1

$\frac{1 - \cos \: a }{1 + \cos \: a } = \frac{(1 - \cos \: a )(1 - \cos\: a) }{(1 + \cos\: a)(1 - \cos \: a ) } = \frac{ {(1 - \cos\: a) }^{2} }{1 - { \cos }^{2} a} \\ = \frac{(1 - { \cos \: a)}^{2} }{ { \sin \: a }^{2} } = {( \frac{ 1 - \cos\: a }{ \sin\: a } )}^{2} = {( \frac{1}{ \sin \: a } - \frac{ \cos\: a}{ \sin\: a } )}^{2} \\ = {( cosec \: a - \cot \: a) }^{2}$
Answer will be option (B).