Cosine Function 68Bff7
1. **State the problem:** We are given the function $y=4\cos\left(2x+\frac{2\pi}{3}\right)-1$ and want to understand its properties.
2. **Formula and explanation:** The function is a cosine function with amplitude, phase shift, and vertical shift. The general form is $y=A\cos(Bx+C)+D$ where:
- $A$ is the amplitude (height of peaks),
- $B$ affects the period (length of one cycle),
- $C$ is the phase shift (horizontal shift),
- $D$ is the vertical shift.
3. **Identify parameters:**
- Amplitude $A=4$
- Angular frequency $B=2$
- Phase shift $C=\frac{2\pi}{3}$
- Vertical shift $D=-1$
4. **Period calculation:**
The period $T$ is given by $T=\frac{2\pi}{|B|}=\frac{2\pi}{2}=\pi$
5. **Phase shift calculation:**
Phase shift $= -\frac{C}{B} = -\frac{\frac{2\pi}{3}}{2} = -\frac{\pi}{3}$
This means the graph shifts to the left by $\frac{\pi}{3}$ units.
6. **Vertical shift:**
The graph is shifted down by 1 unit.
7. **Summary:**
- Amplitude: 4
- Period: $\pi$
- Phase shift: left $\frac{\pi}{3}$
- Vertical shift: down 1
This fully describes the function's behavior.
**Final answer:** The function $y=4\cos\left(2x+\frac{2\pi}{3}\right)-1$ has amplitude 4, period $\pi$, phase shift left $\frac{\pi}{3}$, and vertical shift down 1.