Projection of vectors

[yellow]

I am currently stuck on the second part of this question

a) Find the projection A=(A1,A2,A3) on the direction N=1/sqrt3 (1,1,1)
b) Use this result to find the projection of A on a plane perpendicular to the direction N.


For part a I got (A1+A2+A3)/sqrt3, but I'm not sure how to go about the second part. Using the dot product rule, cos(90)=0 so would the answer be zero?

 

[Deleted member 4993]

I am currently stuck on the second part of this question

a) Find the projection A=(A1,A2,A3) on the direction N=1/sqrt3 (1,1,1)
b) Use this result to find the projection of A on a plane perpendicular to the direction N.


For part a I got (A1+A2+A3)/sqrt3, but I'm not sure how to go about the second part. Using the dot product rule, cos(90)=0 so would the answer be zero?

Hint: Those two orthogonal projections must (vectorially) add up to the original vector.

 

[pka]

I am currently stuck on the second part of this question

a) Find the projection A=(A1,A2,A3) on the direction N=1/sqrt3 (1,1,1)
b) Use this result to find the projection of A on a plane perpendicular to the direction N.


For part a I got (A1+A2+A3)/sqrt3, but I'm not sure how to go about the second part. Using the dot product rule, cos(90)=0 so would the answer be zero?

It needs to be pointed out that these are by no means standard definitions.
Be sure to read your text material carefully.