1. **Stating the problem:** We need to find $\cot(30^\circ + \alpha)$ given that $\cot \alpha = 2$.
2. **Formula used:** The cotangent addition formula is
$$\cot(A+B) = \frac{\cot A \cot B - 1}{\cot A + \cot B}$$
Here, $A = 30^\circ$ and $B = \alpha$.
3. **Known values:** We know $\cot \alpha = 2$.
4. **Calculate $\cot 30^\circ$:**
$$\cot 30^\circ = \sqrt{3}$$
5. **Apply the formula:**
$$\cot(30^\circ + \alpha) = \frac{\cot 30^\circ \cdot \cot \alpha - 1}{\cot 30^\circ + \cot \alpha} = \frac{\sqrt{3} \times 2 - 1}{\sqrt{3} + 2} = \frac{2\sqrt{3} - 1}{\sqrt{3} + 2}$$
6. **Rationalize the denominator:** Multiply numerator and denominator by the conjugate $\sqrt{3} - 2$:
$$\cot(30^\circ + \alpha) = \frac{(2\sqrt{3} - 1)(\sqrt{3} - 2)}{(\sqrt{3} + 2)(\sqrt{3} - 2)}$$
7. **Simplify denominator:**
$$ (\sqrt{3} + 2)(\sqrt{3} - 2) = (\sqrt{3})^2 - 2^2 = 3 - 4 = -1 $$
8. **Expand numerator:**
$$ (2\sqrt{3} - 1)(\sqrt{3} - 2) = 2\sqrt{3} \times \sqrt{3} - 2\sqrt{3} \times 2 - 1 \times \sqrt{3} + 1 \times 2 = 2 \times 3 - 4\sqrt{3} - \sqrt{3} + 2 = 6 - 5\sqrt{3} + 2 = 8 - 5\sqrt{3} $$
9. **Put it all together:**
$$\cot(30^\circ + \alpha) = \frac{8 - 5\sqrt{3}}{-1} = -8 + 5\sqrt{3}$$
**Final answer:**
$$\boxed{\cot(30^\circ + \alpha) = -8 + 5\sqrt{3}}$$
Cotangent Sum 7B7735
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.