Answer:
The length, l, of the ladder is 100 meters
Explanation:
The given scenario forms a right triangle in which the length of ladder is hypotenuse, the distance between the foot of the ladder and the wall is base(as shown in attached diagram) We have to find length of ladder(l)
For this purpose trigonometric ratios can be used. The ratio which includes both base and hypotenuse of triangle is cos θ where θ = 60°
So,

The value of cos 60 is 1/2 or 0.5
So,

Hence,
The length, l, of the ladder is 100 meters