Please leave the steps to solve

Problem 4. (1 point) Consider the function f(x, y) = (ex x) sin(y). Suppose S is the surface 2 = f(x, y). (3) Find a vector which is perpendicular to the level curve of f through the point (5, 6) in the direction in which f decreases most rapidly. vector = (b) Suppose 17 = 7? + 7; + a; is a vector in 3-space which is tangent to the surface S at the point P lying on the surface above (5, 6). What is a? a: Note: You can earn partial credit on this