public duongthang(ClsPoint A, ClsPoint B) { begin = A; end = B; }
public duongthang() { begin = new ClsPoint(0, 0); end = new ClsPoint(0, 0); }
public hinhthoi(ClsPoint X, ClsPoint Y) { begin = X; end = Y; }
public tamgiac(ClsPoint a, ClsPoint b) { begin = a; end = b; }
public hinhthoi() { begin = new ClsPoint(0, 0); end = new ClsPoint(0, 0); }