I know that a proper orthogonal rotation matrix in [itex]R^{2}[/itex] has the form(adsbygoogle = window.adsbygoogle || []).push({});

[cos [itex]\theta[/itex] sin [itex]\theta[/itex]

-sin [itex]\theta[/itex] cos [itex]\theta[/itex]]

which would rotate a vector by the angle [itex]\theta[/itex]. However, I have also seen the matrix

[sin [itex]\theta[/itex] cos [itex]\theta[/itex]

-cos [itex]\theta[/itex] sin [itex]\theta[/itex]]

What type of rotation is this? Is it even a rotation matrix? Thank you in advance.

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# Different rotation matrix, with cosine?

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