Calculus 3

Arctan(y/I if my # 0, f : R2 - R, f(z, y) 10 otherwise. (a) Show that all directional derivatives Daf(0, 0) exist and are equal to 0. (b) Verify that f is not continuous at (0, 0). Hint: What happens to the values of f if the origin is approached along the polar curve r(0) = VO for 0 -> 0 from above? 2