1. **State the problem:** We are given a triangle with sides |CF| = 22 cm, |EF| = 11.8 cm, and the angle \(\angle EFC = 110^\circ\). We need to find the distance |CE| using the cosine rule.
2. **Recall the cosine rule:** For any triangle with sides \(a\), \(b\), and \(c\), and angle \(\theta\) opposite side \(c\), the cosine rule states:
$$c^2 = a^2 + b^2 - 2ab \cos(\theta)$$
3. **Identify the sides and angle:** Here, \(|CE|\) is the side opposite the angle \(\angle EFC = 110^\circ\). The other two sides are \(|CF| = 22\) cm and \(|EF| = 11.8\) cm.
4. **Apply the cosine rule:**
$$|CE|^2 = |CF|^2 + |EF|^2 - 2 \times |CF| \times |EF| \times \cos(110^\circ)$$
Substitute the values:
$$|CE|^2 = 22^2 + 11.8^2 - 2 \times 22 \times 11.8 \times \cos(110^\circ)$$
5. **Calculate each term:**
$$22^2 = 484$$
$$11.8^2 = 139.24$$
6. **Calculate the cosine term:**
$$\cos(110^\circ) = \cos(110 \times \frac{\pi}{180}) \approx -0.3420$$
7. **Calculate the product:**
$$2 \times 22 \times 11.8 \times (-0.3420) = 2 \times 22 \times 11.8 \times -0.3420$$
$$= 519.2 \times -0.3420 = -177.5$$
8. **Substitute back:**
$$|CE|^2 = 484 + 139.24 - (-177.5) = 484 + 139.24 + 177.5 = 800.74$$
9. **Find |CE|:**
$$|CE| = \sqrt{800.74} \approx 28.3 \text{ cm}$$
**Final answer:**
$$|CE| \approx 28.3 \text{ cm}$$
Cosine Rule Ce 30F7E7
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