xac-dinh-tam-va-ban-kinh-mat-cau-ngoai-tiep-hinh-chop-8 xac-dinh-tam-va-ban-kinh-mat-cau-ngoai-tiep-hinh-chop-8xac-dinh-tam-va-ban-kinh-mat-cau-ngoai-tiep-hinh-chop-8