1. **State the problem:**
We need to analyze and sketch the graph of the function $$y = -2 \cos\left(0.25x - \frac{\pi}{8}\right) + 3$$ by finding its amplitude, axis of the curve, period, and phase shift relative to $$y = \cos(x)$$.
2. **Recall the general form and formulas:**
The general cosine function is $$y = A \cos(Bx - C) + D$$ where:
- Amplitude = $$|A|$$
- Axis of the curve (vertical shift) = $$y = D$$
- Period = $$\frac{2\pi}{|B|}$$
- Phase shift = $$\frac{C}{B}$$ (shift to the right if positive, left if negative)
3. **Identify parameters from the given function:**
- $$A = -2$$
- $$B = 0.25$$
- $$C = \frac{\pi}{8}$$
- $$D = 3$$
4. **Calculate amplitude:**
$$\text{Amplitude} = |A| = |-2| = 2$$
5. **Determine the axis of the curve:**
$$y = D = 3$$
6. **Calculate the period:**
$$\text{Period} = \frac{2\pi}{|B|} = \frac{2\pi}{0.25} = 8\pi$$
7. **Calculate the phase shift:**
$$\text{Phase shift} = \frac{C}{B} = \frac{\frac{\pi}{8}}{0.25} = \frac{\pi}{8} \times 4 = \frac{\pi}{2}$$
This means the graph shifts $$\frac{\pi}{2}$$ units to the right relative to $$y = \cos(x)$$.
8. **Interpret the negative amplitude:**
The negative sign in $$A$$ reflects the graph over the axis of the curve (vertical reflection).
**Final summary:**
- Amplitude: 2
- Axis of the curve: $$y = 3$$
- Period: $$8\pi$$
- Phase shift: $$\frac{\pi}{2}$$ units to the right
- Reflection about the axis due to negative amplitude
This information allows you to sketch the graph accurately.
Cosine Graph 997Cf3
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