1. Problem: Two forces of magnitudes 8N and 6N act at an angle of 120° to each other. Find the magnitude of their resultant force. 2. Formula: The magnitude of the resultant $R$ of two forces $F_1$ and $F_2$ acting at an angle $\theta$ is given by the law of cosines: $$R = \sqrt{F_1^2 + F_2^2 + 2 F_1 F_2 \cos \theta}$$ 3. Given values: $F_1 = 8$, $F_2 = 6$, $\theta = 120^\circ$ 4. Calculate $\cos 120^\circ$: $$\cos 120^\circ = -\frac{1}{2}$$ 5. Substitute values into the formula: $$R = \sqrt{8^2 + 6^2 + 2 \times 8 \times 6 \times \left(-\frac{1}{2}\right)}$$ 6. Simplify inside the square root: $$R = \sqrt{64 + 36 - 48} = \sqrt{52}$$ 7. Calculate the square root: $$R = \sqrt{52} = 2 \sqrt{13} \approx 7.21$$ 8. Final answer: The magnitude of the resultant force is approximately $7.21$ N.