please help with my homework

[fiestaboy]

B. Circle in a Square
Write a C++ program that will ask the user to enter the area of a square. Then
the program will display the biggest area of a circle that will fit in a given
square. Using math.h library is not allowed.

[MiiNiPaa]

Using math.h library is not allowed. 

Can you use <cmath> then? :)

Real answer:
if "a" is a square side then:
area of the square (as) = a * a
area of incircle (ac) = Pi * (a * a)/4

Find quotent of incircle area and square area. (ac/as)
Given as and knowing ac/as find ac