ANSWER
2π/3 rad ≈ 2.1 rad
Step-by-step explanation
The arc length of a portion of a circle with central angle θ and radius r is,
In this case, we know that the arc length is s = 10π/3, the radius is 5, and we have to find the central angle. Solving the equation above for θ,
Substitute the known values and solve,
Hence, the angle is 2π/3 radians or 2.1 radians - this last result is rounded to the nearest tenth.