Элементы равностороннего треугольника пронумерованы следующим образом:
1 - сторона а,
2 - радиус R1 вписанной окружности (R1 = a√3 / 6),
3 - радиус R2 описанной окружности (R2 = 2R1),
4 - площадь S = a^2 √3 / 4.
Дан номер одного из этих элементов и его значение.
Вывести значения остальных элементов этого треугольника (в том же порядке).

  
>>> def input_data():
...     parts = input('Enter number and value: ').split()
...     if len(parts) != 2:
...         raise ValueError('Incorrect input: ' + str(parts))
...     number = int(parts[0])
...     value = float(parts[1])
...     return (number, value)
... 
>>> def process_data(number, value):
...     if number == 1:
...         side = value
...     elif number == 2:
...         side = value / (3 ** 0.5 / 6)
...     elif number == 3:
...         side = value / (2 * 3 ** 0.5 / 6)
...     elif number == 4:
...         side = (value / (3 ** 0.5 / 4)) ** 0.5
...     else:
...         raise ValueError('Incorrect number: ' + str(number))
...     out = (
...         side,
...         side * 3 ** 0.5 / 6,
...         2 * side * 3 ** 0.5 / 6,
...         side * side * 3 ** 0.5 / 4
...     )
...     return out
... 
>>> def print_data(side, rin, rout, area):
...     fmt = """\
... 1 - {}
... 2 - {}
... 3 - {}
... 4 - {}
... """
...     print(fmt.format(side, rin, rout, area), end='')
... 
>>> def process_all():
...     data = input_data()
...     data_counted = process_data(*data)
...     print_data(*data_counted)
... 
>>> process_all()
Enter number and value: 1 4
1 - 4.0
2 - 1.1547005383792515
3 - 2.309401076758503
4 - 6.928203230275509
>>> 
>>> process_all()
Enter number and value: 2 1.1547
1 - 3.9999981349995655
2 - 1.1547
3 - 2.3094
4 - 6.928196769725997
>>> 
>>> process_all()
Enter number and value: 3 2.3094
1 - 3.9999981349995655
2 - 1.1547
3 - 2.3094
4 - 6.928196769725997
>>> 
>>> process_all()
Enter number and value: 4 6.9282
1 - 3.999999067499674
2 - 1.1547002691895945
3 - 2.309400538379189
4 - 6.9282
>>> 
>>> process_all()
Enter number and value: 1 2 3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in process_all
  File "<stdin>", line 4, in input_data
ValueError: Incorrect input: ['1', '2', '3']
>>> 
>>> process_all()
Enter number and value: 5 2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in process_all
  File "<stdin>", line 11, in process_data
ValueError: Incorrect number: 5
>>>