4.5 Directional derivatives

1.

(a) $${\frac{1 + \sqrt{3}}{2}}$$(b) $${\frac{\sqrt{3}}{2}}$$

2.

(a) $${\frac{1}{8}}$$(b) $${-\frac{1 + \sqrt{3}}{2}}$$

3.

(a) $${\mbox{in the direction of (1,1) } \sqrt{2}}$$ (b) $${\mbox{in the direction of }(-1,-1)0}$$