Question

Two vector each of magnitude A are inclined at angle θ with each other, then magnitude of resultant vector is

(1) \(A\,cos ^2 \frac {\theta}{2}\)

(2) \(2A\,cos\frac {\theta}{2}\) 

(3) \(2A \,cos \theta\)

(4) \(A\,cos \frac {\theta}{2}\)

Answer 1

(2) \(2A\,cos\frac {\theta}{2}\) 

The magnitude of resultant vector (R) \(=\sqrt {a^2 + b^2 + 2ab \,cos\theta}\)

here a = b = A