1. **Problem Statement:** Find the complex exponential Fourier series representation of the signal $$m(\beta) = \frac{\sin 6\beta}{2} + \frac{\cos 2\beta}{3}$$.
2. **Recall the complex exponential Fourier series formula:**
$$m(\beta) = \sum_{n=-\infty}^{\infty} c_n e^{jn\beta}$$
where $$c_n = \frac{1}{2\pi} \int_{-\pi}^{\pi} m(\beta) e^{-jn\beta} d\beta$$.
3. **Express sine and cosine in terms of complex exponentials:**
$$\sin 6\beta = \frac{e^{j6\beta} - e^{-j6\beta}}{2j}$$
$$\cos 2\beta = \frac{e^{j2\beta} + e^{-j2\beta}}{2}$$
4. **Rewrite the signal using these expressions:**
$$m(\beta) = \frac{1}{2} \cdot \frac{e^{j6\beta} - e^{-j6\beta}}{2j} + \frac{1}{3} \cdot \frac{e^{j2\beta} + e^{-j2\beta}}{2} = \frac{e^{j6\beta} - e^{-j6\beta}}{4j} + \frac{e^{j2\beta} + e^{-j2\beta}}{6}$$
5. **Identify the Fourier coefficients $$c_n$$ by matching terms:**
- For $$n=6$$: $$c_6 = \frac{1}{4j}$$
- For $$n=-6$$: $$c_{-6} = -\frac{1}{4j}$$ (since $$-e^{-j6\beta}$$ term)
- For $$n=2$$: $$c_2 = \frac{1}{6}$$
- For $$n=-2$$: $$c_{-2} = \frac{1}{6}$$
- For all other $$n$$, $$c_n = 0$$.
6. **Final complex exponential Fourier series representation:**
$$m(\beta) = \frac{1}{4j} e^{j6\beta} - \frac{1}{4j} e^{-j6\beta} + \frac{1}{6} e^{j2\beta} + \frac{1}{6} e^{-j2\beta}$$
This matches the original signal exactly.
**Summary:** The signal has nonzero Fourier coefficients only at $$n=\pm 6$$ and $$n=\pm 2$$ with values as above.
Fourier Series 6748E8
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