Hyperbolic Sine in terms of Sine - ProofWiki This identity is also seen in the form: $\sinh z = -i \map \sin {i z}$ which can be seen to follow from the other form by multiplication by $-i$ Also see Hyperbolic Cosine in terms of Cosine Hyperbolic Tangent in terms of Tangent Hyperbolic Cotangent in terms of Cotangent Hyperbolic Secant in terms of Secant Hyperbolic Cosecant in terms of