10. Consider the curve, C, which is the arc of the circle with equation x2 + y = 1 as shown below (note that the arc begins at the point with co-ordinates (1, 0) and ends at the point with co-ordinates (-1, 0)): y C (-1, 0) (1, 0) Let F(x, y) = yi + [(B + 2) + x]j be a vector field in 2. (a) Explain why r(t) = (x(t), y(t)) = (cost, sint) = (cost) i + (sint) j, for 0