3. [15 marks] Calculate the following line integrals. (i) lylds, where L is the unit circle a? + y? = 1. L (ii) xdx + ydy + (x +y - 1)dz, where L is the line segment from (1, 1, 1) to JL (2, 3, 4). (iii) xy'dx - xydy, where L is the circle x2 + y = a in the counterclockwise JL orientation. 4. [10 marks] Find the surface area of z = ary contained inside the cylinder x2 + y? = a2, a > 0