Directional Derivative question. Calculus III/2-variable.

[Unart]

Homework Statement

Let f(x,y,z)=sin(xy+z) and P=(0,-1, pi), Calculate Duf(P) where u is a unit vector making an angle 30°
=θ with dFp?

Homework Equations

This is a two variable problem, where partials are necessary in order to find the gradient formula to get <dFP>. To take the Directional Derivative, from what I know, you require the following equation... <dFP>dot<U>/||u||.

The Attempt at a Solution

from the following I calculated the gradient equation to be
<ycos(xy+z),xcos(xy+z),cos(xy+z)>

with the given gradient equation, I get dFP as <1,0,-1>.

What I cannot figure out is how to get the coordinates for the U vector.

 

[lippyka]

Do I assume it to be <cos30,sin30> or is there a different way to calculate it? I apologise for the late post, I only just realised this was due. Any help would be much appreciated! Thank you!