1. **State the problem:**
We are given two vector equations of lines in 3D:
$$\vec{r}_1 = 3 \hat{i} + \hat{j} - 2 \hat{k} + \lambda (\hat{i} - \hat{j} - 2 \hat{k})$$
$$\vec{r}_2 = 2 \hat{i} - \hat{j} - 56 \hat{k} + \mu (3 \hat{i} - 5 \hat{j} - 4 \hat{k})$$
We want to analyze these lines, for example, to find if they intersect, are parallel, or skew.
2. **Rewrite the parametric form:**
For line 1:
$$x = 3 + \lambda, \quad y = 1 - \lambda, \quad z = -2 - 2\lambda$$
For line 2:
$$x = 2 + 3\mu, \quad y = -1 - 5\mu, \quad z = -56 - 4\mu$$
3. **Set the coordinates equal to find intersection:**
We want to find $\lambda$ and $\mu$ such that:
$$3 + \lambda = 2 + 3\mu$$
$$1 - \lambda = -1 - 5\mu$$
$$-2 - 2\lambda = -56 - 4\mu$$
4. **Solve the system:**
From the first equation:
$$\lambda - 3\mu = -1$$
From the second:
$$-\lambda + 5\mu = -2$$
Add the two equations:
$$\cancel{\lambda} - 3\mu - \cancel{\lambda} + 5\mu = -1 - 2$$
$$2\mu = -3 \implies \mu = -\frac{3}{2}$$
5. **Find $\lambda$ using $\mu$:**
From first equation:
$$\lambda - 3\left(-\frac{3}{2}\right) = -1$$
$$\lambda + \frac{9}{2} = -1$$
$$\lambda = -1 - \frac{9}{2} = -\frac{11}{2}$$
6. **Check the third equation for consistency:**
$$-2 - 2\left(-\frac{11}{2}\right) = -56 - 4\left(-\frac{3}{2}\right)$$
$$-2 + 11 = -56 + 6$$
$$9 \neq -50$$
7. **Conclusion:**
Since the third equation is not satisfied, the lines do not intersect.
8. **Check if lines are parallel:**
Direction vectors:
$$\vec{d}_1 = (1, -1, -2), \quad \vec{d}_2 = (3, -5, -4)$$
Check if $\vec{d}_2 = k \vec{d}_1$ for some scalar $k$:
$$\frac{3}{1} = 3, \quad \frac{-5}{-1} = 5, \quad \frac{-4}{-2} = 2$$
Since these ratios are not equal, lines are not parallel.
9. **Final answer:**
The lines are skew (neither intersecting nor parallel).
**Answer:** The lines do not intersect and are skew lines in 3D space.
Vector Lines 3D 39D90E
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