Let P(x₁,y₁,z₁) be any point on 2x – y + 3z – 4 = 0.

⟹ 2x_{1 –} y₁ + 3z₁ – 4 = 0

⟹ 2x_{1 –} y₁ + 3z₁ = 4 eq(i)

Distance between (x₁,y₁,z₁) and the plane

6x – 3y + 9z + 13 = 0:

We know, the distance of point (x₁,y₁,z₁) from the plane

is given by:

Putting the necessary values,

⟹

⟹

⟹ (using eq (i) )

⟹

∴ the distance between the parallel planes 2x – y + 3z – 4 = 0 and

6x – 3y + 9z + 13 = 0 is units.