F(α) =

| F(α)| = = 1

Cofactors of A are:

C₁₁ = cos α C₂₁ = sin α C₃₁ = 0

C₁₂ = – sin α C₂₂ = cos α C₃₂ = 0

C₁₃ = 0 C₂₃ = – 10 C₃₃ = 1

adj F(α) =

=

So, adj F(α) = …… (i)

Now, [F(α)] ^{– 1} =

And, F( – α) = …… (ii)

=

Hence, [F (α)] ^{– 1} = F( – α)