If ¯r is the position vector of any point on a closed surface S that encloses the volume V then ∬s(¯r.d¯s) is equal to.
Vector equation of a straight line passing through a point given by position vector ¯a parallel to ¯b be is given by ¯r=¯a−λ ¯b, where ¯r , where ¯r is r position vector of a general point on the line and λϵIR