Q.A uniform ladder of length '2L'and mass 'm' leans against a wall in a vertical plane at an angle 'θ' to the horizontal. The floor is rough, having a coefficient of static friction 'µ'. A person of mass 'M' stands on the ladder at a distance 'D' from its base (see figure). If the wall is frictionless, the maximum distance ( Dmax) up the ladder that the person can reach before the ladder slips is ?