Straight lines in Space

To determine a straight line we need a point and a vector, which is called direction vector:

In coordinates

If we work out λ and equalize them:

By doing the cross-product and simplifying in two of them, we obtain:
Example 1:
Example 2:
1.- Find the equations of the straight line that passes through the origin and has the direction of r:
2.- Find the parametric equations of the straight line s:

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