question_answer

A ladder is placed in such a way that its foot is 15 m away from a wall and its top reaches a window 20 m above the ground. The length of the ladder is

A) 35 m

B)  17.5 m 

C)  25 m   

D)  18 m

Correct Answer: C

Solution :

Let BC be the wall and AS be the ladder.

Then, BC = 20 m and AC = 15

\[\therefore \]      \[A{{B}^{2}}=B{{C}^{2}}+A{{C}^{2}}={{(20)}^{2}}+{{(15)}^{2}}\]

\[=(400+225)=625\]

\[\therefore \]      \[AB=\sqrt{625}=25\,\,\text{m}\]