EasyX中的三角函数

#include<stdio.h>
#include<easyx.h>
#include<graphics.h>
#include<math.h>
#define PI 3.14
int main()
{
  initgraph(400, 400);
  setbkcolor(RGB(164, 225, 202));
  cleardevice();
  setaspectratio(1, -1);
  setorigin(200, 200);
  double theta = PI / 2;//初始角度
  double delta = 2 * PI / 5;//两个点之间相差的角度(每循环一次增加的角度72°)
  int r = 100;
  POINT points[5];
  for (int i = 0; i < 5; i++)
  {
    points[i].x = cos(theta + i * delta) * r;
    points[i].y = sin(theta + i * delta) * r;
  }
  polygon(points, 5);
  getchar();
  closegraph();
  return 0;
}