Acircular piece of metal has a radius of 3.5 meters.
the metal sells for $3.25 per square meter.

what is the total cost of the circular piece of metal?

1) we calculate the area of the circular piece of metal.
area=πr²
area=π(3.5 m)²=12.25π m² ≈ 38.48 m²

2)we calculate the total cost of the circular piece of meta by the rule of three.

$3.251 m²
x38.48 m²

x=($3.25 * 38.48m²) / 1 m²=125.06$

125.06$

We can also  calcultate the total cost of the ciucular piece of metal by the ratius.
Ratius=$3.25/1m²

Total cost=ratius * area of the circular piece of metal.
total cost=($3.25/ m²)*(38.48 m²)=$125.06

$125.06