Let the angles in degrees be α - 3δ , α - δ, α + δ, α - 3δ
Sum of the angles = 4α = 360° ⇒ α = 90°
Greatest angle = α + 3δ = 120°
Hence,
3δ = 120° - α = = 120° − 90° = 30°
⇒ δ = 10°
Hence, the angles in degrees are
90° − 30° = 60°; 90° − 10° = 80°
90° + 10° = 100°; 90° + 30° = 120°
In terms of radians, the angles are
π/3,4π/9,5π/9,2π/3.
