Consider the surface z= f(x,y) = 3x+5y+1 and the curve C in the xy-plane given parametrically as x = cost and y = sint where Ost2x. a. Find z'(t). b. Imagine that you are walking on the surface directly above the curve C in the direction of positive orientation. Find the values of t for which you are walking uphill (that is, z is increasing). a. Find the intermediate derivatives. dz ax (Type an expression using x and y as the variables.)