1. ## 2 Vectors problems

Hi Could someone suggest a solution to this vector problems. I have no idea how to start the first question about the Parallelogram.
As for the second question I need to show that the two lines are perpendicular to each other. If the two vectors was in the form of A= 2i+3j+5k , B= -i+4j-2k for example, I would have easily used the dot product rule to determine weather it was perpendicular or not. I don't really know how to use the dot product rule on two vector lines.
Any kind of suggestion is highly appreciated.
Thanks

2. ## Re: 2 Vectors problems

Originally Posted by nova12
If the two vectors was in the form of A= 2i+3j+5k , B= -i+4j-2k for example, I would have easily used the dot product rule to determine weather it was perpendicular or not. I don't really know how to use the dot product rule on two vector lines. Any kind of suggestion is highly appreciated.
For the one above, first show that the two lines intersect.
Then show that their direction vectors are perpendicular.

3. ## Re: 2 Vectors problems

Thanks for the reply Plato. That suggestion helped me a lot. Basically, I just had to find the direction vector and show that it was equal to zero.
I would really appreciate some help on the Parallelogram question Please.

4. ## Re: 2 Vectors problems

It is basically "similar triangles". Segment OQ is 2 times segment OB and segment QR is 2 times QA' (A' is the point on QR where the extension of AX crosses QR). By "similar triangles" OR is exactly 2 times OX.