1. **State the problem:** Solve the equation $$2\cot^2\theta + 3\csc^2\theta = 4\cot\theta + 3$$ for $$-180^\circ \leq \theta \leq 180^\circ$$.
2. **Recall identities:** We know that $$\csc^2\theta = 1 + \cot^2\theta$$.
3. **Substitute:** Replace $$\csc^2\theta$$ in the equation:
$$2\cot^2\theta + 3(1 + \cot^2\theta) = 4\cot\theta + 3$$
4. **Expand and simplify:**
$$2\cot^2\theta + 3 + 3\cot^2\theta = 4\cot\theta + 3$$
$$5\cot^2\theta + 3 = 4\cot\theta + 3$$
5. **Subtract 3 from both sides:**
$$5\cot^2\theta + \cancel{3} - \cancel{3} = 4\cot\theta + \cancel{3} - \cancel{3}$$
$$5\cot^2\theta = 4\cot\theta$$
6. **Rewrite as quadratic in $$\cot\theta$$:**
$$5\cot^2\theta - 4\cot\theta = 0$$
7. **Factor out $$\cot\theta$$:**
$$\cot\theta(5\cot\theta - 4) = 0$$
8. **Set each factor to zero:**
- $$\cot\theta = 0$$
- $$5\cot\theta - 4 = 0 \Rightarrow \cot\theta = \frac{4}{5}$$
9. **Solve $$\cot\theta = 0$$:**
$$\cot\theta = \frac{\cos\theta}{\sin\theta} = 0 \Rightarrow \cos\theta = 0$$
Within $$-180^\circ \leq \theta \leq 180^\circ$$, $$\cos\theta=0$$ at $$\theta = \pm 90^\circ$$.
10. **Solve $$\cot\theta = \frac{4}{5}$$:**
$$\cot\theta = \frac{4}{5} \Rightarrow \tan\theta = \frac{5}{4}$$
11. **Find $$\theta$$:**
$$\theta = \arctan\left(\frac{5}{4}\right) \approx 51.34^\circ$$
12. **Find all solutions in the interval:**
Since $$\tan\theta$$ has period $$180^\circ$$, solutions are:
$$\theta \approx 51.34^\circ$$ and $$51.34^\circ - 180^\circ = -128.66^\circ$$.
13. **Final solutions:**
$$\theta = -180^\circ, -128.66^\circ, 90^\circ, 51.34^\circ$$
(Note: $$-180^\circ$$ is not a solution here; only $$\pm 90^\circ$$ and the two $$\cot\theta=4/5$$ solutions.)
**Answer:** $$\boxed{\theta = -128.66^\circ, -90^\circ, 90^\circ, 51.34^\circ}$$
Cotangent Equation E27272
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