We know that, equation of a plane passing through 3 points,
|

x−x1	y−y1	z−z1
x2−x1	y2−y1	z2−z1
x3−x1	y3−y1	z3−z1

| = 0
⇒ |

x−3	y+1	z−2
2	3	2
−4	0	4

| = 0
⇒ (x - 3) (12 - 0) - (y + 1) (8 + 8) + (z - 2) (0 + 12) = 0
⇒ 12x - 36 - 16y - 16 + 12z - 24 = 0
⇒ 12x - 16y + 12z - 76 = 0
⇒ 3x - 4y + 3z - 19 = 0
Also ,perpendicular distance of P(6, 5, 9) to the plane 3x - 4y + 3z - 19 = 0
=

|3×6−4×5+3×9−19|

√9+16+9

=

6

√34

units