Question
Mathematics Question on Heights and Distances
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
15 m
Explanation
Solution
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)