曲线L的方程为x=R(t-sint),y=R(1-cost)（R>0,0
问题描述：
曲线L的方程为x=R(t-sint),y=R(1-cost)（R>0,0
答
dx=R(1-cost)dt，dy=Rsintdt
∫(2R-y)dx+xdy
=∫R(1+cost)R(1-cost)dt+R(t-sint)Rsintdt
=∫[R^2(1-cos^2t)+R^2(tsint-sin^2t)]dt
=∫R^2tsin^2tdt
=-R^2∫tdcost
=-R^2tcost+R^2∫costdt
=-R^2tcost+R^2sint
答
∵x=R(t-sint),y=R(1-cost)
∴dx=R(1-cost)dt,dy=Rsintdt
∵R>0,0