Question

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

10m
13m
7m
9m​

Answer 1

Answer:

9m is the correct answer

and the working is up in the picture

Answer 2

Answer:

9m

Step-by-step explanation:

Let,

PR be the ladder

PQ be the wall

Given

PR= 15m

PQ= 12m

QR= a =?

Here, angle Q= 90 degree as the wall is straight

In ΔPQR

By pythagoras theorem,

PR² = PQ²+QR²  

(15)²= (12)²+ a²

225 = 144 + a²

225 - 144 = a²

81 = a²                                                                                      

(9)² = a²                                                                          

By cancelling squares, we have,                                

9 = a                                                                              

a= 9 m

∴ the distance of the foot of the ladder from the wall is 9 m.