Answer:
[tex]3,944ft^{2}[/tex] of marble is needed.
Step-by-step explanation:
The picture below represents the top of the Washington Monument, with 4 triangles, one on the base and the other 3 forming the monument.
First of all whe have to find the area of one pyramid:
[tex]A=\frac{height*width}{2}[/tex]
Replacing the values, we have:
[tex]A=\frac{58ft*34ft}{2}[/tex]
[tex]A=986ft^{2}[/tex]
As we have 4 triangles forming the top of the Monument, we have to multiply by 4 to find the quantity of marble to use:
Quantity of marble=Area of each triangle * quantity of triangles
Quantity of marble=[tex]986ft^{2}*4[/tex]
Quantity of marble=[tex]3,944ft^{2}[/tex]