Question

9. If | AB=0, then
1) Either Ä or B is zero
2) Angle between A and B
3) Angle between A and B is 90°
4) Angle between A and
R.O.A-INDIA IIT-JEE/NEET-OLYMPIAD PROGRAMME​

Answer 1

Answer:

not always. A can e 1 and B can be -1 so nope

Answer 2

Answer:

angle between a and b is is 90°