Find the radius of a circle in which the central angle, $a$, intercepts an arc of the given length s. Round to the nearest hundredth as needed.

$a=144,s=102$

The length, $s$, of an arc intercepted by a central angle of radians on a circle of radius $r$ is given by the formula below.

$s=ar$

This formula is only valid if a is measured in radians, so you must use the following formula to convert from degrees to radians.

$d\cdot \frac{\pi}{180}$

What I am confused about is that in the example guide that came along with the question, it gets $\frac{4\pi}{5}rad$ from the degree to radian conversion. How did they get to that answer?

$a=144,s=102$

The length, $s$, of an arc intercepted by a central angle of radians on a circle of radius $r$ is given by the formula below.

$s=ar$

This formula is only valid if a is measured in radians, so you must use the following formula to convert from degrees to radians.

$d\cdot \frac{\pi}{180}$

What I am confused about is that in the example guide that came along with the question, it gets $\frac{4\pi}{5}rad$ from the degree to radian conversion. How did they get to that answer?