1. In each part, evaluate the integral 8 ydx + zdy - xdz along the stated curve. a) The line segment from (0, 0, 0) to (1, 1, 1). b) The twisted cubic x = t, y = 1, z=t from (0, 0, 0) to (1, 1, 1). c ) The helix x = cos (at), y = sin (at), z = t from (1, 0, 0) to (-1, 0, 1)