Formula : Distance = \(\frac{|Ax_1+By_1+Cz_1+D|}{\sqrt{A^2+B^2+C^2}}\)
where (x1,y1,z1) is point from which distance is to be calculated
Therefore ,
Plane r.(3i - 4j + 12k) = 9 can be written in cartesian form as
3x - 4y + 12z = 9
3x - 4y + 12z - 9 = 0
Point = (2i - j - 4k)
Which can be also written as
Point = ( 2 , - 1 , - 4 )