Prove that the lines through `A(0,-1,-1)a n dB(4,5,1)` intersects the line through `C(3,9,4)a n dD(-4,4,4)dot` Also, find their point of intersection.

Explanation

To prove that the lines through points A(0, -1, -1) and B(4, 5, 1) intersect the line through points C(3, 9, 4) and D(-4, 4, 4), we will follow these steps:

### Step 1: Find the parametric equations of the lines AB and CD.

1. **Line AB:**
- The direction vector from A to B is given by \( \vec{AB} = B - A = (4 - 0, 5 - (-1), 1 - (-1)) = (4, 6, 2) \).
- The parametric equations can be written as:
\[
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