9. a Verify stoke's theorem for F = (2x- y)i- y2 j- yzk Where S is the upper half of the sphere x + y + 2 = 1 and C is its boundary b Evaluate [(e dx +2ydy-dz).Using stoke's theorem, where C is the curve C x + y = 4, z = 2 10.a Verify stoke's theorem for F=- yi+ 2yzj+ yk. Where is the upper half of the sphere x + y + z = 1. b Verify stoke's theorem for F= (x + y)7- 2xy taken round the rectangle bounded by the lines x= a, y= 0 and y= b.