I need a function in C that accepts one input number and returns a double input number for the following: Calculates 3.14 times of the square of...

I need a function in C that accepts one input number and returns a double input number for the following: Calculates 3.14 times of the square of input number. For example, if 2 is input then 12.56 should be returned. (e.g. 3.14*2*2 = 12.56)

Can you provide both the C code and an example call to the C code function. Also provide a quick overview of what the function is doing. Include header documentation in the code as well as internal code documentation.