Let A(pheta)= (row1: cos(pheta), sin(pheta) row 2: -sin(pheta), cos (pheta) )
Prove A(pheta)A(alpha)= A(pheta+alpha)
So for the LHS by multiplying matrices I got (row 1: cos(pheta)cos(alpha) -sin (pheta)sin(alpha), -sin(pheta)cos(alpha)-cos(pheta)sin(alpha) row 2: cos(pheta)sin(alpha) + sin(pheta)cos(alpha), -sin(pheta)sin(alpha) + cos(pheta)cos(alpha))
On the RHS I got (row 1: cos(pheta+alpha, sin(pheta +alpha), row 2 -sin(pheta+alpha), cos (pheta+Alpha))
Am I approaching this question in the right way, and if so where would i go from here?