# C++ tan()

This function is defined in <cmath> header file.

`[Mathematics] tan x = tan(x) [In C++ Programming]`

## tan() prototype (As of C++ 11 standard)

```double tan(double x);
float tan(float x);
long double tan(long double x);
double tan (T x); // For integral type
```

## tan() Parameters

The tan() function takes a single mandatory argument in radians (can be positive, negative, or 0).

## tan() Return value

The tan() function returns the value in the range of [-∞, ∞].

## Example 1: How tan() works in C++?

``````#include <iostream>
#include <cmath>

using namespace std;

int main()
{
long double x = 0.99999, result;
result = tan(x);
cout << "tan(x) = " << result << endl;

double xDegrees = 60.0;
// converting degree to radians and using tan() fucntion
result = tan(xDegrees*3.14159/180);
cout << "tan(x) = " << result << endl;

return 0;
}``````

When you run the program, the output will be:

```tan(x) = 1.55737
tan(x) = 1.73205```

## Example 2: tan() function with integral type

``````#include <iostream>
#include <cmath>
using namespace std;

int main()
{
long int x = 6;
double result;

result = tan(x);
cout << "tan(x) = " << result;

return 0;
}
``````

When you run the program, the output will be:

`tan(x) = -0.291006`