Rotation about origin.cpp

#include<stdio.h>
#include<conio.h>
#include<graphics.h>
#include<process.h>
#include<math.h>
void triangle(int x1,int y1,int x2,int y2,int x3,int y3);
void Rotate(int x1,int y1,int x2,int y2,int x3,int y3);
int main()
{
    int gd=DETECT,gm;
    int x1,y1,x2,y2,x3,y3;
    initgraph(&gd,&gm,"c:\\tc\\bgi");
    printf("Enter the 1st point for the triangle:");
    scanf("%d%d",&x1,&y1);
    printf("Enter the 2nd point for the triangle:");
    scanf("%d%d",&x2,&y2);
    printf("Enter the 3rd point for the triangle:");
    scanf("%d%d",&x3,&y3);
    triangle(x1,y1,x2,y2,x3,y3);
    
    
    Rotate(x1,y1,x2,y2,x3,y3);
    setcolor(1);
    triangle(x1,y1,x2,y2,x3,y3);
    getch();
}
void triangle(int x1,int y1,int x2,int y2,int x3,int y3)
{
   line(x1,y1,x2,y2);
   line(x2,y2,x3,y3);
   line(x3,y3,x1,y1);
}
void Rotate(int x1,int y1,int x2,int y2,int x3,int y3)
{
    int x,y,a1,b1,a2,b2,a3,b3;
    float Angle;
    printf("Enter the angle for rotation:");
    scanf("%f",&Angle);
    cleardevice();
    Angle=(Angle*3.14)/180;
    a1=x1*cos(Angle)-y1*sin(Angle);
    b1=x1*sin(Angle)+y1*cos(Angle);
  a2=x2*cos(Angle)-y2*sin(Angle);
    b2=x2*sin(Angle)+y2*cos(Angle);
  a3=x3*cos(Angle)-y3*sin(Angle);
    b3=x3*sin(Angle)+y3*cos(Angle);
    printf("Rotate");
    triangle(a1,b1,a2,b2,a3,b3);
}