ok...Compute the line integral bounded by C of ydx - xdy (i dont know if that was a typo if thats normal, ive never seen an integral like that)

where C is the upper semicircle of radius 1 oriented from (1; 0) to (-1; 0) (i.e. counter-clockwise).

when i did the problem i got 0 as the answer, but my teachers answer page says -Pi. any ideas?

also i used C = <cos t, sin t> from 0 to Pi.