rotation

#include
#include
#include
#include
#include
#include
float x1,y1,x2,y2,x,y,x3,y3,x4,y4,a;
int ch;
int main(void)
{
int gdriver = DETECT, gmode, errorcode;
clrscr();
initgraph(&gdriver, &gmode, "c:\\tc\\bgi");
errorcode = graphresult();
if (errorcode != grOk)
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1);
}
do
{
cout<<" #############MAIN-MENU###############\n";
cout<<" ROTATION\n";
cout<<" 1.LINE\n";
cout<<" 2.RECTANGLE\n";
cout<<" 3.TRIANGLE\n";
cout<<"enter your choice:0 for exit:\n";
cin>>ch;
switch(ch)

{
case 1: cout<<"enter the values of line coordinates:";
cin>>x1>>y1>>x2>>y2;
cout<<"enter the value for angle of rotation:";
cin>>a;
cleardevice();
line(x1,y1,x2,y2);
a=a*(3.14/180);
x1=(x1*cos(a))-(y1*sin(a));
y1=(x1*sin(a))+(y1*cos(a));
x2=(x2*cos(a))-(y2*sin(a));
y2=(x2*sin(a))+(y2*cos(a));
cout<<"now hit a key to see rotation:";
getch();
line(x1,y1,x2,y2);
break;

case 2: cout<<"enter the top left coordinates:";
cin>>x1>>y1;
cout<<"enter the bottom right coordinates:";
cin>>x2>>y2;
cout<<"enter the value for angle of rotation:";
cin>>a;
cleardevice();
rectangle(x1,y1,x2,y2);
a=a*(3.14/180);
x1=(x1*cos(a))-(y1*sin(a));
y1=(x1*sin(a))+(y1*cos(a));
x2=(x2*cos(a))-(y2*sin(a));
y2=(x2*sin(a))+(y2*cos(a));
cout<<"now hit a key to see rotation:";
getch();
rectangle(x1,y1,x2,y2);
break;
case 3: cout<<"enter coordinates of line1:\n";
cin>>x1>>y1>>x2>>y2;
cout<<"enter coordinates for relative line:\n";
cin>>x3>>y3;
cout<<"enter the angle of rotation:\n";cin>>a;
cleardevice();
line(x1,y1,x2,y2);
moveto(x2,y2);
lineto(x3,y3);
moveto(x3,y3);
lineto(x1,y1);
a=a*(3.14/180);
x1=(x1*cos(a))-(y1*sin(a));
y1=(x1*sin(a))+(y1*cos(a));
x2=(x2*cos(a))-(y2*sin(a));
y2=(x2*sin(a))+(y2*cos(a));
x3=(x3*cos(a))-(y3*sin(a));
y3=(x3*sin(a))+(y3*cos(a));
cout<<"now hit a key to see rotation:";
getch();
moveto(x1,y1);
lineto(x2,y2);
moveto(x2,y2);
lineto(x3,y3);
moveto(x3,y3);
lineto(x1,y1);
break;
case 0: break;
default:cout<<"invalid choice";break;
}}while(ch!=0);
getch();
closegraph();
}