Find the limit or show that it does not exist. r2 + sin? y (a) lim (z.y)-(0,0) 2 + y? (b) lim (22 + y?) In(2 + y?). (1,y)(0,0) (a) Use the definition of partial derivative as limit to find fy, given that f(r, y): r+ y2" (b) Use the definition of directional derivative as limit to find the derivative of f(r, y) = e" cos y in the direction of 0 = 4 %3D