3. Let S be part of the plane x + y + z = 1 in the first octant (ie. x20, y20, z21) with normal oriented upward (in the positive direction) and let C be its boundary. oriented counter-clockwise from above. If F = (x²-y²)! + (y²-z²) + (z²x²) verify Stokes' theorem by calculating both E.dr and ff, curlEndo.