Between two fixed boundaries there is a two dimensional liquid motion due to a source of strength m at the point (r=a, 0 =0) and an equal sink at the point (r=b,0 =0). Show that the stream function is -m tan -1 r²(a²-b¹) /sin 40 r³-r¹ (a¹ + b¹) cos 40+ a¹b²​