The RotationMatrix(t) command returns the $\mathrm{2x2}$ rotation Matrix corresponding to the angle t, measured in radians.

The RotationMatrix(t,v) command returns the $\mathrm{3x3}$ rotation Matrix corresponding to the angle t, where the rotation axis is given by v.  The direction of rotation is determined by using the right-hand rule with respect to v.

$\mathrm{with}\left(\mathrm{Student}\left[\mathrm{LinearAlgebra}\right]\right)\:$

$\mathrm{RotationMatrix}\left(\frac{\mathrm{\pi }}{4}\right)$

$\left[\begin{array}{cc}\frac{\sqrt{2}}{2}& -\frac{\sqrt{2}}{2}\\ \frac{\sqrt{2}}{2}& \frac{\sqrt{2}}{2}\end{array}\right]$

$\mathrm{RotationMatrix}\left(\frac{\mathrm{\pi }}{3}\,⟨0\,1\,0⟩\right)$

$\left[\begin{array}{ccc}\frac{1}{2}& 0& \frac{\sqrt{3}}{2}\\ 0& 1& 0\\ -\frac{\sqrt{3}}{2}& 0& \frac{1}{2}\end{array}\right]$

$\mathrm{RotationMatrix}\left(1.3\,⟨1\,1\,1⟩\right)$

$\left[\begin{array}{ccc}0.5116658857& \mathrm{-0.3121435208}& 0.8004776350\\ 0.8004776350& 0.5116658857& \mathrm{-0.3121435208}\\ \mathrm{-0.3121435208}& 0.8004776350& 0.5116658858\end{array}\right]$