posted by Lolo .
A ladder, 6m long rests against a wall. The foot of the ladder is 2.5m away from the base of the wall. The ladder has a 'safe angle' with the ground between 60(degrees) and 70(degrees). what are the safe limits for the distance of the foot of the ladder to the wall.
If the base of the ladder is at distance b from the wall, and the ladder makes an angle θ with the ground,
b/6 = cosθ
sec 60° = .5
sec 70° = .34
so 6*2 = 3
6*.34 = 2.04
so, the base may safely be between 2 and 3 feet from the wall.