Question

The length of a ladder is exactly equal to the height of the wall it is leaning against.If the lower end of the ladder is kept on a stool of height 3 m and the stool is kept 9 m away from the wall the upper end of the ladder coincides with the top of the wall.Then the height of the wall is

• A. 15 m
• B. 12 m
• C. 18 m
• D. 11 m

Answer 1

The Correct Option is A

Let's take the length of the ladder and the wall be x.
The formula of pythagoras theorem is,
Hypotenuse² = Perpendicular² + Base²
c² = a² + b²  (Here Hypotenuse is c, Perpendicular is b and Base is b)
x² = (x-3)² + 9²
By Solving the equation, we get 
x = 15 m.
The correct option is (A)