## Trigonometry 7th Edition

$\frac{2}{5}$
We know that if $A$ is a real number and $B\gt0$, then the graphs of $y=Asin(Bx)$ and $y=Acos(Bx)$ will have an amplitude of $|A|$. Therefore, the amplitude of the graph of $y=-\frac{2}{5}sin x$ is $|-\frac{2}{5}|=\frac{2}{5}$.