Documentation

Mathematica Teacher's Edition

Built-in Functions

Algebraic Computation

Formula Manipulation

ExpToTrig

ExpToTrig[expr] converts exponentials in expr to trigonometric functions.

ExpToTrig generates both circular and hyperbolic functions.
ExpToTrig tries when possible to give results that do not involve explicit complex numbers.
See The Mathematica Book on the web: Section 1.4.5 and Section 3.3.7.
See also: TrigToExp, TrigReduce, ComplexExpand.

Further Examples