3. Consider the function f(x,y) = (e-r) cos(y). Suppose S is the surface z = = f(x,y). (a) Find a vector which is perpendicular to the level curve of f through the point (2,3) in the direction in which ƒ decreases most rapidly. (b) Use the previous part to construct the equation of the tangent line to the level curve off at (2,3). (c) Suppone +43+ ak is a vector in 3-space which is tangent to the surface S at the point Pon the surface, above (2,3). What is a? I