mot hinh thang co day be bang 3/5 day lon va co chieu cao bang 23cm.Nguoi ta mo rong hinh thang bang cach keo dai day be cho bang day lon da duoc1 hinh chu nhat ,sau khi mo rong thi dien tich tang them 207cm vuong .Tinh dien tich hinh thang luc chua mo rong?