Answer
Find out the how high up the wall does the ladder reach .
To proof
let us assume that the height of the wall be x .
As given
A 25-foot long ladder is propped against a wall at an angle of 18° .
as shown in the diagram given below
By using the trignometric identity
\(cos\theta = \frac{Base}{Hypotenuse}\)
now
\(\theta = 18^{\circ}\)
Base = wall height = x
Hypotenuse = 25 foot
Put in the trignometric identity
\(cos18^{\circ} = \frac{x}{25}\)
\(cos18^{\circ} = \bar{0.9510565162}\)
x = 23.8 foot ( approx)
Therefore the height of the ladder be 23.8 foot ( approx) .
