Exercise: Circle and Sphere |2|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Write a program that inputs a radius *r* from the user and computes the
area of a circle with radius *r* and the volume of a sphere with radius
*r*. (Print 2 digits after the decimal point)

**Hint:** You can use the :math:`\color{purple}{\texttt{math}}` module
to import the :math:`\color{purple}{\texttt{pi}}` constant.

.. container:: sampleio

   Sample I/O:

.. |2| image:: ../../figures/difficulty_two.png
   :class: difficulty

.. code:: python

   Input:
   5

   Output:
   circle area: 78.54
   sphere volume: 523.60

   Input:
   4.25

   Output:
   circle area: 56.75
   sphere volume: 321.56