28. Suppose you follow the spiral path C: x = cos t, y= sin t, and z= t, for t20, through the domain of the function xyz w = f(x,y,z) = 2 +1 Complete parts (a) and (b) below. First, find some intermediate derivatives. dw dx (Type an expression using x, y, and z as the variables.) dx %3D dt (Type an expression using t as the variable.) dw %3D ду (Type an expression using x, y, and z as the variables.)