#include<stdio.h>
#include<graphics.h>
#include<math.h>
#define PI 3.14
int main()
{
    void welecome();
    initgraph(1200,600);
    setbkcolor(RED);
    cleardevice();
    welecome();
    getchar();
    return 0;
}
void welecome()
{
    settextcolor(YELLOW);
   
    int x = 500, y =200;
    for (int i = 0; i < 50; i++)
    {
        settextstyle(i, 0, L"华文行楷");
        int x = 500 + int(180 * sin(PI * 2 * i / 60));
        int y = 200 + int(180 * cos(PI * 2 * i / 60))；
        cleardevice();
        outtextxy(x, y, L"情人节");
        outtextxy(x + 80, y + 60, L"献给某某某");
        Sleep(30);
    }
    getchar();
    cleardevice();
}

不清楚这两行确定文字的坐标具体是怎样得到的，求解释
int x = 500 + int(180 * sin(PI * 2 * i / 60));
int y = 200 + int(180 * cos(PI * 2 * i / 60))；