What is the unit normal vector to the surface x+y+z=1x + y + z = 1x+y+z=1?
⟨13,13,13⟩\langle \frac{1}{\sqrt{3}}, \frac{1}{\sqrt{3}}, \frac{1}{\sqrt{3}} \rangle⟨31,31,31⟩
⟨1,1,1⟩\langle 1, 1, 1 \rangle⟨1,1,1⟩
⟨12,12,0⟩\langle \frac{1}{\sqrt{2}}, \frac{1}{\sqrt{2}}, 0 \rangle⟨21,21,0⟩
⟨0,0,1⟩\langle 0, 0, 1 \rangle⟨0,0,1⟩