visual c++画五边形的算法，不知道是怎么弄出来的？

Question

visual c++画五边形的算法，不知道是怎么弄出来的

Answer 1

void pentangon1(HDC hdc,int R,int x,int y)//R为五边形边长，x，y为离原点距离，A、B、C、D、E为五个顶点，用画笔画出的一个正五边形
{
const double Pi=3.1415926;
const double Rd54=54*Pi/180;//度数与弧度的转换
const double Rd72=72*Pi/180;
HPEN hP;//
hP=CreatePen(PS_SOLID,1,RGB(255,0,0));//
SelectObject(hdc,hP);
MoveToEx(hdc,x+int(R*sin(Rd54)),y+0,NULL);//A
LineTo(hdc,x+int(2*R*sin(Rd54)),y+int(R*cos(Rd54)));//A->B
LineTo(hdc,x+int(R*(1+cos(Rd72))),y+int(R*(cos(Rd54)+sin(Rd72))));//B->C
LineTo(hdc,x+int(R*cos(Rd72)),y+int(R*(cos(Rd54)+sin(Rd72))));//C-D
LineTo(hdc,x+0,y+int(R*cos(Rd54)));//D->E
LineTo(hdc,x+int(R*sin(Rd54)),y+0);//E-A
DeleteObject(hP);//
}