If $\vec a$ and $\vec b$are unit vectors and θ is the angle between them, then $|\frac{\vec a-\vec b}{2}|$ is:
Answer & explanation
Correct answer: option 1
$|\frac{\vec a-\vec b}{2}|^2=\frac{1}{4}(|\vec a|^2+|\vec b|^2-2\vec a.\vec b)=\frac{1}{4}(1+1-2\cos θ)=sin^2\frac{θ}{2}⇒|\frac{\vec a-\vec b}{2}|=sin\frac{θ}{2}$