Compute the arc length of a circle given its radius and central angle in degrees.
Arc length is the distance along the curved part of a circle. It equals the radius times the central angle in radians.
Arc Length
L = r × θ (θ in radians)
Multiply degrees by π/180. For example, 90° = π/2 radians.
It equals the circumference: 2πr (360° gives θ = 2π).