The parametric equations of a parabola are x = t 2 + 1, y = 2t + 1. The Cartesian equation of its directrix is

Question

Philoid · Accepted Answer

Given the parametric equations of a parabola x = t² + 1 and y = 2t + 1.

Consider ,

⇒

⇒ (y - 1)² = 4(x - 1)

Comparing with the standard form of parabola (y - a)² = 4b(x - c) we get,

⇒ 4b = 4

⇒ b = 1

⇒ The equation of the directrix is x - c = - b

⇒ Directrix is x - 1 = - 1

⇒ Directrix is x = 1 - 1

⇒ Directrix is x = 0

∴The correct option is A