如果曲线L的方程为y=W(x)(a≤x≤b),则有 f.d(dx 令y=(x) ds=I+(y)dx 如果方程为极坐标形式：L:r=r(0)(@≤0≤B),则 f(xy)ds -f(r(cs0)sin)d x=rcose y=rsin ds=vr2+(r)"de 如果曲线 L 的方程为y =ψ(x) (a ≤ x ≤ b),则有 ∫L f (x, y)ds 如果方程为极坐标形式: L :r = r(θ ) (α ≤θ ≤ β ),则 f x y s L∫ ( , )d ∫ = βα f (r(θ ) cosθ , r(θ )sinθ ) 1 (x) dx 2 +ψ′ (θ ) (θ ) dθ 2 2 r + r′ ∫ = ba f (x,ψ (x)) y =ψ ( ) x 2 令 d 1 ( )d s = + y′ x x r = cosθ y r = sinθ 2 2 d ()d srr = + ′ θ