Question

Consider two vectors a and b. Select all the correct statements above the two vectors above. 

1. a is perpendicular to a×b.
2. a×b is parallel to b×a.
3. If a×b=0 then a=0 or b=0.
4. If a and b are parallel vectors then $\mathbf{a}\cdot\mathbf{b}=|\mathbf{a}||\mathbf{b}|$
5. If a and b are parallel vectors then a×b=0.

Answer 1

the correct statements are

1. a is perpendicular to a×b.
2. a×b is parallel to b×a.
3. If a and b are parallel vectors then a×b=0.