Question

prove that sec a + tan a - 1 x sec a - tan a+ 1 is equal to 2 tan a
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Answer 1

See carefully, it is same as the formula of (a^2-b^2)=(a-b)×(a+b)

So, we can write it as

((Sec a)^2 - (Tan a -1)^2)

Now,solving further and applying transformation formula , you will get.

1+(Tan a)^2 -(Tan a)^2 -1+ 2Tan a {apply (a-b)^2=a^2 +b^2 -2ab}

so, solving further and canceling same terms

answer will be

=2 Tan a