28:43 Nimechanganyikiwa, kwa nini tunafika vekta sifuri hapa, haipaswi kuwa vekta 3, -1 https://matrixcalc.org/en/#%7B%7B1 ,2%7D,%7B3,6%7D%7D%2A%7B%7B3%7D,%7B-1%7D%7D####[['vekta sifuri', 'Mathematical_Related_Concept', 'NEU'], ['vekta 3, -1', 'Mathematical_Related_Concept', 'NEU']]