The MCD has decided to put up a lamp post of certain height at a certain distance from the edge of the road. The lamp is inclined such that it makes angle of `45^@` with the centre of the road.The lamp focus coverts a total area within `30^@`.The distance from the centre of the road should be the lamp post be,so as to light up exactly the whole width of the road and also height of the lamp post will be: