Given:
The base of 40-foot ladder is 8 feet from the wall.
To find:
How high is the ladder on the wall (round to the nearest foot).
Solution:
Ladder makes a right angle triangle with wall and ground.
We have,
Length of ladder (hypotenuse)= 40 foot
Base = 8 foot
We need to find the perpendicular to get the height of the ladder on the wall.
Let h be the height of the ladder on the wall.
According to the Pythagoras theorem,
![Hypotenuse^2=Base^2+Perpendicular^2](https://img.qammunity.org/2022/formulas/mathematics/high-school/7t36b8r09zt78n0wnyh0xx7hiol93gqv7q.png)
![(40)^2=(8)^2+(h)^2](https://img.qammunity.org/2022/formulas/mathematics/high-school/ps2403ctzxy78ecc7gm8vl58b6akekl7yp.png)
![1600=64+h^2](https://img.qammunity.org/2022/formulas/mathematics/high-school/vpn71hul2nfl6hbo6obpy37rsg93wz6nsh.png)
![1600-64=h^2](https://img.qammunity.org/2022/formulas/mathematics/high-school/9zlqtcpn84dmcz8hsy4ahcfaagp0biotru.png)
![1536=h^2](https://img.qammunity.org/2022/formulas/mathematics/high-school/80j6wdsvjbclexwfammvjqh8yg4efb04vh.png)
Taking square root on both sides.
![\pm √(1536)=h](https://img.qammunity.org/2022/formulas/mathematics/high-school/rjykahfe11iao64r7415lasdsn2k8y8rdt.png)
![\pm 39.1918358=h](https://img.qammunity.org/2022/formulas/mathematics/high-school/rjrt53qv61j5t5ueabe4o4aqhahon8d2q7.png)
Height cannot be negative. Round to the nearest foot.
![h\approx 39](https://img.qammunity.org/2022/formulas/mathematics/high-school/20xvh25kcak2hv9qfkc49fo9degsxws2zo.png)
Therefore, the height of the ladder on the wall is 39 foot.