$\"\"$

The permeter of a sector of a circle $\"\"$ is equal to is the sum of the arc length $\"\"$ and two times the radius $\"\"$ .

$\"\"$ .

Arc length : $\"\"$ .

Since perimeter of a sector of a circle is 10 times the length of the circle’s radius $\"\"$ .

Substitute $\"\"$ and $\"\"$ in $\"\"$ .

$\"\"$

Sector’s central angle is $\"\"$ radians.

Sarah is correct.

$\"\"$

Sarah is correct.supplementary angle.