Given equation of the parabola is y² - 4y + 4x = 0

⇒ y² - 4y = - 4x

⇒ y² - 4y + 4 = - 4x + 4

⇒ (y - 2)² = - 4(x - 1)

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

⇒ 4b = 4

⇒ b = 1

⇒ The vertex is (c, a) = (1, 2)

⇒ The focus is (b + c, a) = (1-1, 2) = (0, 2)

⇒ The equation of the axis is y - a = 0 i.e, y - 2 = 0

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

⇒ Directrix is x - 1 = 1

⇒ Directrix is x = 1 + 1

⇒ Directrix is x = 2

⇒ Length of latus rectum is 4b = 4.