void monteCarlo() {
	double przedial = 100000;
	double a = 0;
	double b = 3.14159265359;
	srand((unsigned)time(NULL));
	//std::cout << RAND_MAX;
	double ymax = 1.0;
	double ymin = 0.0;
	double ile=0;
	for (int i = 0; i < przedial; i++) {
		double x= (double)(std::rand()) / (double)RAND_MAX;;
		double y= (double)(std::rand()) / (double)RAND_MAX;
		x *= 3.14159265359;

		//std::cout << x << " " << y << std::endl;
	//	system("pause");
		if ((y > 0) && (y < fx(x)))
			ile++;


	}
	double calka =( ile/przedial) * 3.14*1.0 ;
	std::cout << calka<<std::endl;
}