Question

A ladder 20 m long is placed against a vertical wall of height 10 m, determine the distance between foot of the ladder and the wall and also the inclination of the ladder with the horizontal.

• A. $10\sqrt{3},{30}^{\circ }$
• B. $20\sqrt{2},{20}^{\circ }$
• C. $10\sqrt{6},{60}^{\circ }$
• D. $6\sqrt{1}0,10$

Answer 1

Answer: (A)

$10\sqrt{3},{30}^{\circ }$

$\sin \theta =\frac{p}{h}=\frac{10}{20}=\frac{1}{2}\theta =\frac{\pi }{6}=\theta ={30}^{\circ }$

now,

$\cos \theta =\frac{AB}{BC}\cos \frac{\pi }{6}=\frac{AB}{BC}\frac{\sqrt{3}}{2}=\frac{AB}{20}\sqrt{3}=\frac{AB}{10}AB=10\sqrt{3}$