Hermitian inner product btw 2 complex vectors & angle btw them

[raja0088]

What is the relationship btw the Hermitian inner product btw 2 complex vectors & angle btw them.
x,y are 2 complex vectors.
$$\theta$$ angle btw them

what is the relation btw $$x^{H}$$y and cos($$\theta$$)??
Any help will be good?

 

[g_edgar]

What is definition of "angle" in complex space? Same as the underlying real space? Then, of course, use the underlying real inner product, which is the real part of the complex inner product.