Question

Prove that `((tan a +sec a +1 )( tan a -sec a +1 )) / tana =2`?

Answer 1

`LHS=((tan a +sec a +1 )( tan a -sec a +1 )) / tana`
`=((tan a +1 )^2 -sec^2 a ) / tana`

`=(tan^2a+2tan a +1 -sec^2 a ) / tana`

`=(sec^2a+2tan a -sec^2 a ) / tana`

`=(2tan a ) / tana`

`=2 =RHS`