44. Find the mass of a thin will don is proportional to the distance above the xy-plane. 45-48 Find the work done by the force field F on a particle that moves along the curve C. he 45. Far, )=nitz'i C: x = >2 from (0, 0) to (1, 1) 46. F(x, v) = (x2 + x)i+ ( - x2y)j C:x= t, y= 1/t (15t