What is the length of arc S?
(The angle in the figure is a central angle in radians)

Answer:
π/90 or 0.0035 units
Step-by-step explanation:
equation: length of the arc = ∠of the angle/360 * circumference
Substitute: S = 0.4/360 * 10π --> C = 2πr
Simplify: S = 1/900 * 10π
Simplify: S = π/90 ≈ 0.003489 units