
3-3 (j) Parallel vectors
Point 4 of 7 — The Vector (Cross) Product and the Scalar Triple ProductQuestion bank: 0 questions (0 with pictures)
04 3-3 (j) Parallel vectors
Condition
- Two non-zero vectors are parallel if and only if , that is
- Equivalent form: . If they have the same direction; if they are opposite.
- If a component of is zero, the matching component of must also be zero.
✍️ Worked examples
Example 7: Find and if is parallel to .
Solution:
- .
- gives .
- gives .
- The vectors are in the same direction since the ratio is positive.
Example 8: A vector is parallel to and . Find .
Solution:
- and , so .
- or .
Example 9: Decide whether and are parallel, perpendicular, or neither.
Solution:
- Ratios: , : not equal, so not parallel.
- Dot product: , so not perpendicular.
- They are neither.
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