# Vector calculus - line integral

Suppose that F is an inverse square force field; this is, F(r) = cr/ |r|$$^{3}$$ for some constant c, where r = xi + yj + zmbfk. Find the work done by F in moving an object from a point P1 along a path to a point P2 in terms of the distances d1 and d2 from these points to the origin.

Not exactly sure where to start, do i still find the integral of F with respect to dr..., and there's no r(t).. like other questions, so i am lost.