The **`tanh()` function** returns the *hyperbolic tangent* of a number. To be more specific, it returns the hyperbolic tangent of a number in the *radians float value*. 

Figure 1 shows the mathematical representation of the `tanh()` function.

> The `math.h` header file is required for this function.

# Syntax
```c
double tanh(double num)
```
# Parameter
This function requires a `number` representing an `angle` in `radians` as a parameter.

>Use the following formula to convert `degrees` to `radians`
```c
radians = degrees * ( PI / 180.0 )
```

# Return value
`tanh()` returns the #key# hyperbolic tangent of a number: in radians float value #key# that is sent as a parameter.

# Example


#include<stdio.h>
//header file
#include<math.h>

int main() {
    //positive number in radians
    printf("The hyperbolic tangent of %lf is %lf \n", 2.3, tanh(2.3));

    // negative number in radians
    printf("The hyperbolic tangent of %lf is %lf \n", -2.3, tanh(-2.3));

    //converting the degrees angle into radians and then applying tanh()
    // degrees = 45.0
    // PI = 3.14159265
    // result first converts degrees to radians then apply tanh
    double result=tanh(45.0 * (3.14159265 / 180.0));
    printf("The hyperbolic tangent of %lf is %lf \n", 45.0, result);


}

What is tanh() in C?

The tanh() function in C returns the hyperbolic tangent of a number in radians. It requires <math.h>.