Cho sinα=3/5(90∘<α<180∘). Khi đó:15/22Cho \(\sin \alpha = \frac{3}{5}\left( {{{90}^\circ } < \alpha < {{180}^\circ }} \right)\). Khi đó:a\(\cos \alpha > 0\)ĐúngSaib\({\cos ^2}\alpha = \frac{{16}}{{25}}\)ĐúngSaic\(\cos \alpha = \frac{4}{5}\)ĐúngSaid\[\tan \alpha = \frac{3}{4}\]ĐúngSaiGiải thícha – Saib – Đúngc – Said – Sai