Answer:
793 liters of washing fluid is needed
Step-by-step explanation:
step 1
Find the slant height of the triangular faces of pyramid
we know that
The lateral area of a square pyramid is equal to the area of its four triangular faces
so
![LA=4[\frac{1}{2}bl]](https://tex.z-dn.net/?f=LA%3D4%5B%5Cfrac%7B1%7D%7B2%7Dbl%5D)
where
b is the base of triangle (is the same that the length of the square base)
l is the slant height
To find out the slant height we need to apply the Pythagorean Theorem
so

we have


substitute



step 2
Find the lateral area of the pyramid
![LA=4[\frac{1}{2}bl]](https://tex.z-dn.net/?f=LA%3D4%5B%5Cfrac%7B1%7D%7B2%7Dbl%5D)
we have


substitute
![LA=4[\frac{1}{2}(35.42)(27.96)]](https://tex.z-dn.net/?f=LA%3D4%5B%5Cfrac%7B1%7D%7B2%7D%2835.42%29%2827.96%29%5D)

step 3
Find out how much window washing fluid is needed
we know that
2 L of washing fluid cover 5 square meters
so
using proportion

Round up
793 liters of washing fluid is needed