Question

find the distance from the point (-5,-2,5) to the plane -x-2y-3y=2

Answer 1

First, are you sure it's not ON the plan already? Important to check.

\(\dfrac{|-(-5)-2(-2)-3(5)-2|}{\sqrt{(-1)^{2}+(-2)^{2}+(-3)^{2}}}\)

It works in 2D. Why would it fail in 3D? A direction cosine doesn't care how many dimensions it's in.