1 #include <iostream>
2
3 using namespace std;
4
5 class Trapezium
6 {
7 private:
8 int x1,y1,x2,y2,x3,y3,x4,y4;
9 public:
10 void initial(){x1=0,x2=0;x3=0;x4=0;y1=0;y2=0;y3=0;y4=0;return;}
11 void GetPosition(int&,int&,int&,int&,int&,int&,int&,int&);
12 void Area()
13 {
14 double s;
15 s=((x2-x1)+(x4-x3))*(y2-y4)/2.0;
16 cout<<s<<endl;
17 return;
18 }
19 };
20
21 void Trapezium::GetPosition(int& a,int& b,int& c,int& d,int& e,int& f,int& g,int& h)
22 {
23 x1=a;y1=b;x2=c;y2=d;x3=e;y3=f;x4=g;y4=h;
24 return;
25 }
26
27 int main()
28 {
29 int x[4],y[4];
30 Trapezium one;
31 for(int i=0;i<4;i++) cin>>x[i]>>y[i];
32 one.initial();
33 one.GetPosition(x[0],y[0],x[1],y[1],x[2],y[2],x[3],y[3]);
34 one.Area();
35 return 0;
36 }
