and note that this is equivalent to rotating through by , which is the matrix
Given that the following matrix creates an anticlockwise rotation of the x-y plane about the origin through an angle :
use this fact to obtain the standard trig identities:
I can obtain the identities using geometry and I can see how the matrix transformation creates an anticlockwise rotation, but I can't see how to use the matrix trransformation to generate the identities. Can anyone help?