#include<iostream>
#include<cmath>
using namespace std;
void main()
{
	setlocale(LC_ALL, "ru");
	double a,b,z,f,x,d1,d2,d3;
	int n;
	cout << "Введите z: ";
	cin >> z;
	if (z < 0)
	{
		x = z;
		cout << "z < 0 -> x = z" << endl;
	}
	else
	{
		x = sin(z);
		cout << "z >= 0 -> x = sin(z)" << endl;
	}
	cout << "Выберите функцию:\n1)2*x\n2)x^2\n3)x/3 "<<endl;
	cin >> n;
	switch (n)
	{
	case 1:
		f = 2 * x;
		cout << "f(x) = 2x" << endl;
		break;
	case 2:
		f = pow(x, 2);
		cout << "f(x) = x^2" << endl;
		break;
	case 3:
		f = x / 3;
		cout << "f(x) = x/3" << endl;
		break;
	}
	cout << "Введите a: ";
	cin >> a;
	cout << "Введите b: ";
	cin >> b;
	d1 = 2 * a * pow(sin(x), 2) / 3;
	d2 = 3 * b * pow(cos(f), 2) / 4;
	d3 = d1 - d2;
	cout << "Ответ = " << d3 << endl;
}