Question

If a man has a ladder of 18 m and needs to reach the top of the wall of $9\sqrt{3}m$. What is the required angle between ladder and wall?

• A. ${30}^{\circ }$
• B. ${60}^{\circ }$
• C. ${45}^{\circ }$
• D. ${15}^{\circ }$

Answer 1

The correct option is A

${30}^{\circ }$

Given that, the length of the ladder (h) = 18 m
the height of the wall (b) $=9\sqrt{3}m$


$cos\theta =\frac{heightofthewall}{lengthoftheladder}=\frac{b}{h}=\frac{9\sqrt{3}}{18}=\frac{\sqrt{3}}{2}$

$\Rightarrow cos\theta =cos{30}^{\circ }$
$\Rightarrow \theta ={30}^{\circ }$