T=(x'ï¼y'ï¼z')
=(1ï¼2tï¼3t^2)
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cosα=1/â(1+4t^2+9t^4)
cosβ=2t/â(1+4t^2+9t^4)
cosγ=3t^2/â(1+4t^2+9t^4)
ä»è
â«P(x,y,z)dx+Q(x,y,z)dy+R(x,y,z)dz
=â«(Pcosα+Qcosβ+Rcosγ)ds
=â«(P+Q·2t+R·3t^2)/â(1+4t^2+9t^4) ds