The formula for the circumference of a circle is π x diameter
Since we already know the circumference, we divide that by π to get the diameter:
circumference = π x diameter
so
circumference / π = diameter
Now lets do this:
31.4 / π = 9.9949... (this is the diameter)
-----------------------------------------------------------------------
The formula for the area of a circle is π r²
To get the radius, we just halve the diameter:
9.9949.. / 2 = 4.99746...
Now that we know the radius we can use the formula:
π x r²
= π x 4.99746²
= 78.46ft²
So the area is:
78.46ft²
