Given:
Length of the ladder = 9.85 m
The height to the top of the ladder is 5 m more than the distance between the wall and the foot of the ladder.
To find:
The height to the top and the distance between the wall and the foot of the ladder.
Solution:
let x be the distance between the wall and the foot of the ladder. Then the height to the top of the ladder is (x+5).
Pythagoras theorem: In a right angle triangle,
![Hypotenuse^2=Base^2+Perpendicular^2](https://tex.z-dn.net/?f=Hypotenuse%5E2%3DBase%5E2%2BPerpendicular%5E2)
In the given situation, hypotenuse is the length of ladder, i.e., 9.85 m. The base is x m and the height is (x+5) m.
Using the Pythagoras theorem, we get
![(9.85)^2=x^2+(x+5)^2](https://tex.z-dn.net/?f=%289.85%29%5E2%3Dx%5E2%2B%28x%2B5%29%5E2)
![97.0225=x^2+x^2+10x+25](https://tex.z-dn.net/?f=97.0225%3Dx%5E2%2Bx%5E2%2B10x%2B25)
![0=2x^2+10x+25-97.0225](https://tex.z-dn.net/?f=0%3D2x%5E2%2B10x%2B25-97.0225)
![0=2x^2+10x-72.0225](https://tex.z-dn.net/?f=0%3D2x%5E2%2B10x-72.0225)
Here,
. Using the quadratic formula, we get
![x=\dfrac{-b\pm \sqrt{b^2-4ac}}{2a}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B-b%5Cpm%20%5Csqrt%7Bb%5E2-4ac%7D%7D%7B2a%7D)
![x=\dfrac{-10\pm \sqrt{(10)^2-4(2)(-72.0225)}}{2(2)}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B-10%5Cpm%20%5Csqrt%7B%2810%29%5E2-4%282%29%28-72.0225%29%7D%7D%7B2%282%29%7D)
![x=\dfrac{-10\pm \sqrt{676.18}}{4}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B-10%5Cpm%20%5Csqrt%7B676.18%7D%7D%7B4%7D)
Approximating the value, we get
![x=\dfrac{-10\pm 26}{4}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B-10%5Cpm%2026%7D%7B4%7D)
![x=\dfrac{-10+26}{4},\dfrac{-10-26}{4}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B-10%2B26%7D%7B4%7D%2C%5Cdfrac%7B-10-26%7D%7B4%7D)
![x=\dfrac{16}{4},\dfrac{-36}{4}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B16%7D%7B4%7D%2C%5Cdfrac%7B-36%7D%7B4%7D)
![x=4,-9](https://tex.z-dn.net/?f=x%3D4%2C-9)
Distance cannot be negative so ![x\neq -9.](https://tex.z-dn.net/?f=x%5Cneq%20-9.)
Now we have ![x=4](https://tex.z-dn.net/?f=x%3D4)
![x+5=4+5](https://tex.z-dn.net/?f=x%2B5%3D4%2B5)
![x+5=9](https://tex.z-dn.net/?f=x%2B5%3D9)
Therefore, the base is 4 m and the height is 9 m.