In learning how to rotate vertices about an arbitrary axis in 3D space, I came across the following matrices, which I need to calculate the inverse of to properly "undo" any rotation caused by them:

![enter image description here](https://i.stack.imgur.com/aXDE3.png)

![enter image description here](https://i.stack.imgur.com/IjFwS.png)

How can I get the inverse of both of these matrices?  

Thanks.