=1 We know that the equation of hyperbola is ⇒sin‌2α=cos2α(e2−1) ⇒sin‌2α+cos2α=cos2α⋅e2 ⇒e2=1+tan2α=sec2α⇒e=sec‌α ∴ae=cos‌α⋅‌
1
cos‌α
=1 Co-ordinate of foci are (±αe,0) i.e. (±1,0) Hence, abscissae of foci remain constant when α varies.