Nested function problem

[chipx]

Hi everyone, I created this nested function to solve this formula: sqrt(sin(x)*(cos(x)) but it doesn't work. Where am I wrong?
Thanks
chipx

this is the code:

Output:
[output]import math

def f1(x):
    a = math.sqrt(b)
    def f2(x):
        b = math.sin(x)*c
        def f3(x):
            c = math.cos(x)
        return c
    return b
    return a


f1(5)  

[/output]