Using Theorem 5.8 prove Eq. (5.60).
THEOREM 5.8
Let Σ be a (p x p) partitioned covariance matrix. The coefficients that maximize the correlation between the linear combinations u =aTX(1) and v = βTX(2) are the latent vector solutions of the systems of equations.
where the matrices are as in Eq. (5.52) and λ = μ =aTΣ12β is the maximum correlation.