To find the distance between two parallel planes given by the equations:

1. $x - 2y + 3z = 1$
2. $x - 2y + 3z = -10$

The general formula for the distance $d$ between two parallel planes $Ax + By + Cz + D_1 = 0$ and $Ax + By + Cz + D_2 = 0$ is:

$d = \frac{|D_1 - D_2|}{\sqrt{A^2 + B^2 + C^2}}$

Here, the planes are:

• $x - 2y + 3z = 1$, which can be written as $1x - 2y + 3z - 1 = 0$, so $A = 1$, $B = -2$, $C = 3$, and $D_1 = -1$.
• $x - 2y + 3z = -10$, which can be written as $1x - 2y + 3z + 10 = 0$, so $D_2 = 10$.

Now, applying the formula: