radical in c code example

Example 1: root in C

#include <stdio.h>
#include <math.h>

int main()
{
    double num = 6, squareRoot;

    squareRoot =  sqrt(num);
    printf("Square root of %lf =  %lf", num, squareRoot);

    return 0;
}

Example 2: sqrt in c

#include <math.h>
double sqrt(double arg);