Question

A 15 m long ladder reached a window 12 m high from the ground on placing it against a wall at a distance 'a'. Find the distance of the foot of the ladder from the wall.

• A. 3m
• B. 6m
• C. 9m
• D. 12m

Answer 1

The correct option is C 9m


Let AC be the ladder and A be the window.
Given: AC = 15 m, AB = 12 m, CB = 'a' m
In right angled triangle ACB,
using Pythagoras theorem we get
$\Rightarrow (AC{)}^2=(CB{)}^2+(AB{)}^2\Rightarrow (15{)}^2=(a{)}^2+(12{)}^2\Rightarrow 225=a^2+144\Rightarrow a^2=225-144=81\Rightarrow a=\sqrt{81}=9cm$
Thus, the distance of the foot of the ladder from the wall is 9m.