### 2.21.5 Simplify : `simplify`

`simplify` simplifies the expression.

As with all automatic simplifications, do not expect miracles,
you will have to use specific rewriting rules if it does not work.

Input :

`simplify((sin(3*x)+sin(7*x))/sin(5*x))`

Output :

`4*(cos(x))``^`

`2-2`

**Warning** `simplify` is more efficient in `radian` mode (check
`radian` in the `cas` configuration
or input `angle_radian:=1`).