The function .
Theorem :
\Any trigonometric function is continuous at every number on its domain.
\Consider and
.
The domain of the trigonometric function is
and it is continuous in its domain.
The domain of polynomial function is
and it is continuous in its domain.
Domain :
\All possible values of is the domain of the function.
The domain of is
.
The function is continuous at every number in its domain.
Domain of the function is
.
Domain of the function is .