The amplitude of a sinusoidal function $y = a \sin(x)$ is the absolute value of the coefficient $a$.

For the given function $y = -3 \sin(x)$:

1. The coefficient $a$ is $-3$.
2. The amplitude is the absolute value of $-3$, which is $3$.

So, the amplitude of $y = -3 \sin(x)$ is $3$.

Would you like more details or have any questions?

Here are 8 relative questions that expand on this topic:

1. What is the period of the function $y = -3 \sin(x)$?
2. How does the negative sign in front of the amplitude affect the graph of $y = -3 \sin(x)$?
3. What are the maximum and minimum values of the function $y = -3 \sin(x)$?
4. How would the graph of $y = -3 \sin(x)$ compare to the graph of $y = 3 \sin(x)$?
5. What is the phase shift of the function $y = -3 \sin(x)$?
6. How would you determine the amplitude of a function like $y = -3 \sin(2x)$?
7. What is the general form of a sinusoidal function?
8. How do you find the amplitude of a function $y = -3 \cos(x)$?

Tip: The amplitude of a sinusoidal function is always positive, as it represents the distance from the midline to the peak (or trough) of the wave.