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.(i + j + k) + 17 = 0 can be written in cartesian form as
x + y + z + 17 = 0
Point = (i + 2j + 5k)
Which can be also written as
Point = (1 , 2 , 5)