Question

A ladder 15 meters long just reaches the top of a vertical wall. If the ladder makes an angle of ${60}^o$ with the wall, find $m$ if the height of the wall is $\frac{15}{m}$.

Answer 1

Angle ${60}^{\circ }=\theta$,
Hypotenuse (length of the ladder) $=15meters$

Adjacent (height of the wall) $=\frac{15}{m}$

$\cos \theta =\frac{adj}{15}$

$\cos \left({60}^{\circ }\right)=\frac{1}{2}=\frac{\frac{15}{m}}{15}$

$\frac{1}{2}=\frac{1}{m}$

$\therefore m=2$