Phan mem C.a.R (Circle and Rules) la phan mem thuoc nhom “Dynamic Geometry”, tuc la phan mem mo phong cac hinh hinh hoc dong. Hoan toan tuong tu nhu cac phan mem Cabri II, Geometer Sketchpad, GeoGebra, Euklides, phan mem CaR bao gom cac cong cu dung de thiet ke va ve cac doi tuong hinh hoc tren mat phang.

Phien ban dau tien cua phan mem nay duoc xay dung va phat trien boi mot giao su Toan hoc noi tieng nguoi Duc, ong Rene. Grothmann. Ong la giao su toan hoc truong dai hoc Katholische Universitet Eichstutt cua Cong Hoa Lien Bang Duc.

Phien ban ma CENTEA Data gioi thieu la CAR Metal do mot hoc tro cua GS Grothmann ten la Hakenholz, nguoi Phap, phat trien. CAR Metal co source nguon lay hoan toan tu C.A.R nhung da thay doi hoan toan giao dien de tro thanh mot phan mem khac han voi giao dien than thien hon va de su dung hon. CAR Metal tat nhien cung la mot phan mem ma nguon mo va mien phi.

Dac diem noi bat nhat cua phan mem nay la he thong cac cong cu da duoc phan loai va sap xep lai trong mot khung cua so nho phia ben phai man hinh chinh. Viec sap xep lai cac bieu tuong cong cu nay lam cho phan mem tro thanh than thien va de su dung hon so voi phien ban goc C.A.R cua phan mem.

De chay duoc phan mem nay, may tinh cua quy Thay Co can duoc cai may ao Java (JRE) phien ban tu 1.4.x tro len. Quy Thay Co co the download chuong trinh JRE tai day