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