1. **Problem Statement:** Find the y-coordinate of point A on the unit circle at an angle of $\frac{3\pi}{2}$ radians. 2. **Relevant Formula:** On the unit circle, a point at angle $\theta$ has coordinates $(\cos\theta, \sin\theta)$. 3. **Apply the formula:** For $\theta = \frac{3\pi}{2}$, $$x = \cos\left(\frac{3\pi}{2}\right), \quad y = \sin\left(\frac{3\pi}{2}\right)$$ 4. **Evaluate the trigonometric functions:** - $\cos\left(\frac{3\pi}{2}\right) = 0$ - $\sin\left(\frac{3\pi}{2}\right) = -1$ 5. **Interpretation:** The point A is at $(0, -1)$, so the y-coordinate of point A is $-1$. **Final answer:** The y-coordinate of point A is $-1$.