#include <cmath>
    double tan( double arg );

The tan() function returns the tangent of arg, where arg is given in radians. If arg is infinite, tan() will return NAN and raise a floating-point exception.

C++ also provides the following overloaded forms:

    #include <cmath>
    float tan( float arg ); // same as tanf() in C99
    long double tan( long double arg ); // same as tanl() in C99

Related Topics: acos, asin, atan, atan2, cos, cosh, sin, sinh, tanh