Question

(d) (1 + cos a) (1 - cos a) /(1 + sin a) (1 - sin a)= tan2 a​

Answer 1

$\frac{(1 - \cos(a))(1 + \cos(a)) }{(1 - \sin(a) )(1 + \sin(a)) } =$

$\frac{1 - {cos}^{2}(a) }{1 - {sin}^{2}(a) } =$

$\frac{ {sin}^{2}(a) }{ {cos}^{2}(a) } =$

${tan}^{2} (a)$