If vectors A = cos ω t i + sin ω t j and B = cos (ω t)/2 i + sin (ω t)/2 j are functions of time, then the value of t at which they are orthogonal to…

If vectors $\displaystyle \vec{A}=\cos \omega t \hat{i}+\sin \omega t \hat{j}$ and $\displaystyle \vec{B}=\cos \frac{\omega t}{2} \hat{i}+\sin \frac{\omega t}{2} \hat{j}$ are functions of time, then the value of $\displaystyle t$ at which they are orthogonal to each other is :