曲線積分,其中L是從A(0,0)沿y=sinx到點(diǎn)B(π/2,1)的曲線段,則其值是:()
A.1-e
B.e
C.2(e-1)
D.0
L是區(qū)域D:x2+y2≤-2x的正向周界,則(x3-y)dx+(x-y2)dy等于:()
A.2π
B.0
C.(3/2)π
D.-2π
設(shè)L是從點(diǎn)(0,0)沿y=1-|x-1|至點(diǎn)(2,0)的折線段,則曲線積分-ydx+rdy等于()
A.0
B.-1
C.2
D.-2