Question:P, Q, R are the points on the sides BC, CA, AB of the triangle ABC such that \(BP:PC = CQ:QA = AR:RB = m:n\) . If \(\Delta \) denotes the area of the \(\Delta ABC\) , then the forces \(\overrightarrow {AP} ,\overrightarrow {BQ} ,\overrightarrow {CR} \) reduce to a couple whose moment is