Question

Solve this ( Chap: Vectors)

If resultant of A and B is perpendicular to A, what is the angle between A and B?

$(1) { \cos }^{ - 1} ( \frac{A}{B} ) \\ \\ (2){ \cos }^{ - 1} ( \frac{ - A}{B} ) \\ \\ (3){ \sin }^{ - 1} ( \frac{A}{B} ) \\ \\ (4){ \sin }^{ - 1} ( \frac{ - A}{B} )$

Answer 1

Angle is equal to option (2).
See the pic for solution.

Answer 2

Answer:

option 2 is the right answer