A TV-tower stands vertically on a bank of a canal. From a point on the other bank directly opposite the tower, the angle of elevation of the top of the tower is `60^(@)`. From another point 20 m away from this point on the line joining this point to the foot of the tower, the angle of elevation of the top of tower is `30^(@)` (see fig.) . FInd the height of the tower and the width of the canal.