急~高等微積分請大師幫忙

Let Cr denote the circle of radius r about the origin in the xy-plane, oriented counterclockwise as viewed from the positive y-axis. Suppose F is a C1 vector field on the complement of the y-axis in R3 such that ∫C1 F‧dx = 5 and curl F(x,y,z) = 3j + (zi-xk) / (x^2+z^2)^2 .Compute ∫Cr F‧dx... show more Let Cr denote the circle of radius r about the origin in the xy-plane, oriented counterclockwise as viewed from the positive y-axis. Suppose F is a C1 vector field on the complement of the y-axis in R3 such that ∫C1 F‧dx = 5 and curl F(x,y,z) = 3j + (zi-xk) / (x^2+z^2)^2 .Compute ∫Cr F‧dx for every r .
Update: 1.題目打錯 是 in the xz-plane
Update 2: r > 1時 ρ 的上下界是r~1?
還是應該是 1~r?
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