et . (a) find . <0,0,0> (b) what does your answer to part (a) tell you about where is the circle in the -plane, oriented clockwise? 0 (c) if is any closed curve, what can you say about ? 0 (d) now let be the half circle in the -plane with , traversed from to . find by using your result from (c) and considering plus the line segment connecting the endpoints of .