Cho sin a = − 1/2 . Tính sin ( pi − alpha) .3/39Cho\(\sin a = - \frac{1}{2}\). Tính\(\sin (\pi - a)\).\(\sin (\pi - a) = \frac{1}{2}.\)\(\sin (\pi - a) = - \frac{1}{2}.\)\(\sin (\pi - a) = \frac{{\sqrt 3 }}{2}.\)\(\sin (\pi - a) = - \frac{{\sqrt 3 }}{2}.\)Giải thíchChọn B Ta có: \(\sin (\pi - a) = \sin a = - \frac{1}{2}.\)