We are looking for the arc length of a segment of the circumference
we will use the next formula
[tex]\text{arc length=2}\pi r(\frac{\theta}{360})[/tex]where r is the radius, and theta is the angle.
in this case
r=100ft/2=50ft
theta=81°
we susbtitute
[tex]\text{arc length=2}\pi(50)(\frac{81}{360})=70.69ft[/tex]She swam 70.69ft
