Question

If $A.B=A\times B$, then angle between $A$ and $B$ is

• A. ${45}^o$
• B. ${30}^o$
• C. ${60}^o$
• D. ${90}^o$

Answer 1

The correct option is A ${45}^o$

Given : $A.B=A\times B$

Taking mod on both sides, $|A.B|=|A\times B|$

OR $|A||B|\cos \theta =|A||B|\sin \theta$

OR $\sin \theta =\cos \theta$

OR $\tan \theta =1$

$⟹\theta ={45}^o$