Вычислить значение выражения

a =  a * (M_PI / 180)

#include <math>

z1 = pow((cos(a) - cos(b)), 2.0) - pow((sin(a)-sin(b)), 2.0)

z2 = -4*sin(a-b/2*sin*a-b/2)*cos(a + b);

/* Define _USE_MATH_DEFINES before including math.h to expose these macro
 * definitions for common math constants.  These are placed under an #ifdef
 * since these commonly-defined names are not part of the C/C++ standards.
 */

#define _USE_MATH_DEFINES

#include<cmath>

#include <iostream>
#define _USE_MATH_DEFINES
#include <cmath>
using namespace std;
int main(){
    double z1,z2,a,b;
    cout << "vvedite a,b";
    cin >> a >> b;
z1 = pow((cos(a) - cos(b)), 2.0) - pow((sin(a)-sin(b)), 2.0);
z2 = -4*sin(a-b/2*sin*a-b/2)*cos(a + b);
cout << "z1:" << z1 << endl;
cout << "z2" << z2 << endl;
system ("pause");
return 0;
}

 z2 = -4*sin(a-b/2)*sin(a-b/2)*cos(a + b);

z2 = -4 * sin(a - b / 2 * sin * a - b / 2) * cos(a + b);