Cho sin α . cos β = 1 2 ; cos α . sin β = 1/3 . Tính sin ( α + β ) .

18/39

Cho \(\sin \alpha .\cos \beta = \frac{1}{2}\); \(\cos \alpha .\sin \beta = \frac{1}{3}\). Tính \(\sin \left( {\alpha + \beta } \right)\).

\(\sin \left( {\alpha + \beta } \right) = - \frac{1}{6}\).

\(\sin \left( {\alpha + \beta } \right) = \frac{5}{6}\).

\(\sin \left( {\alpha + \beta } \right) = \frac{2}{3}\).

\(\sin \left( {\alpha + \beta } \right) = \frac{1}{6}\).

Giải thích

Chọn B

Ta có \(\sin (\alpha + \beta ) = \sin \alpha \cdot \cos \beta + \cos \alpha \cdot \sin \beta = \frac{1}{2} + \frac{1}{3} = \frac{5}{6}.\)