The radius of the circle is 13 in, therefore the circumference is
2π(13) = 26π in.
The central angle of the circle is 2π rad.
The arc has a length of 5 in.
If the central angle of the arc is θ rad, then
13θ = 5
θ = 5/13 = 0.385 rad
Answer: θ = 0.385 rad