Laplacian of a plane wave in Cartesian coordinates

[xz5x]

This is what I got for Nabla and Laplace of plane wave. I have problems when I try to write out it with x, y, z coordinates. Can somebody help me? Thanks!


http://img213.imageshack.us/img213/9532/85490316.jpg


http://img528.imageshack.us/img528/6835/f41cab97f649df5431127b5.png

 

[Muphrid]

What problems do you have? You should get the same thing, just written in terms of the components of $k$ and $r$.

 

[xz5x]

@Muphrid

I know the result, but I have problems with procedure. Can you write down this equation; or just the start? Thanks!

 

[Muphrid]

What's $k \cdot r$ when written in terms of cartesian coordinates?

 

[xz5x]

Yes.