function meanAngle (angleList)
  local sumSin, sumCos = 0, 0
  for i, angle in pairs(angleList) do
    sumSin = sumSin + math.sin(math.rad(angle))
    sumCos = sumCos + math.cos(math.rad(angle))
  end
  local result = math.deg(math.atan2(sumSin, sumCos))
  return string.format("%.2f", result)
end

print(meanAngle({350, 10}))
print(meanAngle({90, 180, 270, 360}))
print(meanAngle({10, 20, 30}))