50g Hyperbolic Identity Question

[Bill Triplett]

When doing symbolic math using complex arguments, various different math engines respond to sinh(X + Y*i) by simplifying in terms of trig functions which do not have imaginary arguments. For example, one engine responds with ...

sinh(X) * cos(Y) + cosh(X) * sin(Y) * i

Question: How can we have a HP 50g respond in this way when given sinh(X + Y * i) as input? I know folks are often using the Prime nowadays, but the venerable 50g has a charm of its own.