1. **State the problem:** Two men pull a tree stump with forces of 700 N and 850 N at a 40° angle between them. We need to find the resultant force. 2. **Formula used:** The resultant force $R$ when two forces $F_1$ and $F_2$ act 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. **Identify values:** - $F_1 = 700$ N - $F_2 = 850$ N - $\theta = 40^\circ$ 4. **Calculate $R^2$:** $$R^2 = 700^2 + 850^2 + 2 \times 700 \times 850 \times \cos 40^\circ$$ 5. **Calculate each term:** $$700^2 = 490000$$ $$850^2 = 722500$$ $$2 \times 700 \times 850 = 1190000$$ $$\cos 40^\circ \approx 0.7660$$ 6. **Substitute and simplify:** $$R^2 = 490000 + 722500 + 1190000 \times 0.7660$$ $$R^2 = 490000 + 722500 + 911540$$ $$R^2 = 2124040$$ 7. **Find $R$ by taking the square root:** $$R = \sqrt{2124040} \approx 1457.4$$ 8. **Interpretation:** The resultant force on the tree stump is approximately 1457 N. **Final answer:** $$\boxed{1457 \text{ N}}$$