A woman pulls a sled which, together with its load, has a mass of [math] kg. Let [math] be the acceleration due to gravity. If her arm makes an angle of [math] with her body (assumed vertical) and the coefficient of friction (a positive constant) is [math], the least force, [math], she must exert to move the sled is given by [math] If [math], find the maximum and minimum values of [math] for [math].

maximum force = Newtons
minimum force = Newtons