What is the angle between force and displacement for minimum work?

We have,
$\mathrm{W} = \mathrm{F}\times \mathrm{s}\times \cos \mathrm{\theta }----\left(1\right)$

For minimum work done $\cos \mathrm{\theta }$ need to be minimum,
We know the value of $\cos \mathrm{\theta }$ is minimum for $\mathrm{\theta }={90}^{°}$, i.e., $\cos {90}^{°}=0$.
$\Rightarrow \mathrm{W}=\mathrm{F}\times \mathrm{s}\times 0$
$\Rightarrow \mathrm{W}=0$
Therefore, work done is $0$ when the angle between the force and the displacement is $90^{\mathrm{o}}$.