#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

double arcsin(float x)
{
	return atan(x/(sqrt(1 - x*x)));
}
int main () 
{
	double x1, x2;
	cout<<setprecision(20)<<M_PI<<endl;
	x1 = M_PI/4;
	x2 = arcsin(sin(x1));
	cout << endl;
	cout << " x1 = " << x1 << endl;
	cout << " x2 = " << x2 << endl;
	cout << " blad bezwzgledny:"<< abs(x1 - x2);
	return 0;
}