IfA=⎛⎜⎝cosx−sinx0sinxcosx0001⎞⎟⎠,then(adjA)−1=
|A|=1⇒(adjA)=I⇒(A(adjA))−1=I−1⇒(adjA)−1A−1=1⇒(adjA)−1=A
If F(x)=[cosx−sinx0,
sinxcosx0
0,0,1]
show that F(x) F(y)=F(x+y)