Question

cho \(\sin\alpha=\dfrac{\sqrt{5}}{3}\\ tinh\\ \cos2\alpha\sin\alpha\)

Answer 1

\(\sin\alpha=\dfrac{\sqrt{5}}{3}\Rightarrow\alpha=48,1896851\)

\(\Rightarrow\cos2\alpha\sin\alpha=-\dfrac{1}{9}\cdot\dfrac{\sqrt{5}}{3}=-\dfrac{\sqrt{5}}{27}\)

Answer 2

\(\cos2\alpha sin\alpha=\left(1-2sin^2\alpha\right)sin\alpha=\left(1-2.\dfrac{5}{9}\right)\dfrac{\sqrt{5}}{3}=-\dfrac{\sqrt{5}}{27}\)