∫c1+c2 a・dr = ∫c1 a・dr +∫c2 a・dr = 18+..

dr=(-3sint,3cost,0)dt
a=(9cost^2,3sint,0)
a*dr=(-27sintcost^2+9costsint)dt=9cost^3+4.5sint^2 (0->pai)
=-9-9=-18
18-18=0