A survey line BAC crosses a river, A and C being on the near and opposite banks respectively. A perpendicular AD,40 m long, is set out at A. If the bearings of AD and DC are 48 ∘ 30 ′and 288 ∘ 30 ′ respectively, draw the sketch and find the bearing of the chain line BAC and also the chainage of C when that of A is 207.8 m.