Consider the function f(x,y,z) = sin(xyz).

[3) Compute the gradient Vf(1r,0,1r/2). (b) Compute the directional derivative % at the point (1r, 0, 1r] 2), where u = (7'5. 0. 7'5)- (c) Find all the directions 11 for which the directional derivative % is zero in the point (11'. (l, \"fr/2). (d) What are the directions 11 for which the above directional derivative: reaches its maximum? miniimun