The magnitude of the resultant of two vectors of magnitude 3 units and 4 units in 5 units. What is the angle between the two vectors?
π2
The magnitude R of the resultant vector →R of two vectors →A and →B inclined at an angle θ is given by R2=A2+B2+2ABcosθ
Here, R2=A2+B2, i.e., 52=32+42
⇒cos θ=0
∴θ=π2
Hence, the correct choice is (b).