Determine the equation of the given conic in xy-coordinates when the coordinate axes are rotated through the indicated angle.
xy = x + y, ϕ = π/4

The color contrast between the open ocean and the lagoon between the spit and the mainland. the greater concentration of suspended sediments in the lagoon gives the waters a more turbid appearance. the source of sediment in the lagoon is (are) [(rivers and streams from the mainland) (wind-borne sediment from the spit) (ocean waves washing over the spit) (all of these contribute)].