Sine Wave Equation
1. **Problem Statement:** Given a sine wave oscillating between -2 and 2 with x-axis labeled in multiples of $\frac{\pi}{3}$, and two full cycles from 0 to $\frac{10\pi}{3}$, find the equation of the sine wave.
2. **Formula and Explanation:** The general form of a sine wave is:
$$y = A \sin(Bx + C) + D$$
where:
- $A$ is the amplitude (half the distance between max and min values),
- $B$ affects the period (period $= \frac{2\pi}{B}$),
- $C$ is the phase shift,
- $D$ is the vertical shift.
3. **Determine Amplitude $A$:** The wave oscillates between -2 and 2, so amplitude is:
$$A = \frac{2 - (-2)}{2} = \frac{4}{2} = 2$$
4. **Determine Vertical Shift $D$:** Since the wave oscillates symmetrically about 0, vertical shift is:
$$D = 0$$
5. **Determine Period and $B$:** Two full cycles occur from 0 to $\frac{10\pi}{3}$, so one full cycle period $T$ is:
$$T = \frac{10\pi/3}{2} = \frac{10\pi}{6} = \frac{5\pi}{3}$$
Using the period formula:
$$T = \frac{2\pi}{B} \implies B = \frac{2\pi}{T} = \frac{2\pi}{\frac{5\pi}{3}} = \frac{2\pi \times 3}{5\pi} = \frac{6}{5}$$
6. **Determine Phase Shift $C$:** The graph starts at $x=0$ with $y=0$ and follows a sine wave pattern, so no horizontal shift:
$$C = 0$$
7. **Final Equation:** Substitute values into the general form:
$$y = 2 \sin\left(\frac{6}{5}x\right)$$
**Answer:** The equation of the sine wave is:
$$y = 2 \sin\left(\frac{6}{5}x\right)$$