Question

Prove that (sec theta + tan theta - 1)(sec theta - tan theta + 1) = 2tan theta
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Answer 1

(secΘ+tanΘ-1)(secΘ-tanΘ+1)

=sec²Θ-secΘtanΘ+secΘ+secΘtan-tan²Θ+tanΘ-secΘ+tanΘ-1

=2tanΘ+(sec²Θ-tan²Θ)-1

=2tanΘ+1-1

=2tanΘ