1. **State the problem:** We need to find the length of the cable (side $AB$) in triangle $ABC$ where $AC=105$ m, angle $\angle BAC=12^\circ$, and the hill's inclination angle $\angle ACB=58^\circ$.
2. **Identify the angles:** The triangle's angles are $\angle BAC=12^\circ$, $\angle ACB=58^\circ$, and the remaining angle $\angle ABC$ can be found by the triangle angle sum rule:
$$\angle ABC = 180^\circ - 12^\circ - 58^\circ = 110^\circ$$
3. **Use the Law of Sines:** The Law of Sines states:
$$\frac{AB}{\sin(58^\circ)} = \frac{AC}{\sin(110^\circ)} = \frac{BC}{\sin(12^\circ)}$$
We want to find $AB$, so:
$$AB = AC \times \frac{\sin(58^\circ)}{\sin(110^\circ)}$$
4. **Calculate the sine values:**
$$\sin(58^\circ) \approx 0.8480$$
$$\sin(110^\circ) \approx 0.9397$$
5. **Calculate $AB$:**
$$AB = 105 \times \frac{0.8480}{0.9397}$$
6. **Simplify the fraction:**
$$\frac{0.8480}{0.9397} \approx 0.9029$$
7. **Final calculation:**
$$AB \approx 105 \times 0.9029 = 94.8$$
**Answer:** The length of the cable required is approximately **94.8 m**.
Law Of Sines 3F2A56
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