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## C++ atan()

Last Updated on Wednesday 5th Oct 2022

## atan

The C++ atan() function returns the inverse tangent of an angle in radian.It is defined in <cmath> header file.

### Syntax

```			```
atan(x)

```

```

### Parameters

The `atan()` function takes a one argument. It can be positive, negative, or zero.

### Return value

The `atan()` function returns the value in the range of `[-π/2, π/2]`.

### atan() prototype [As of C++ 11 standard]

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

```

```

## arc tan

### Example 1: C++ atan()

```			```
#include <stdio.h>
#include <math.h>

#define PI 3.14159265

int main () {
double param, result;
param = 4.4;
result = atan(param) * 180 / PI;
printf ("The arc tangent of %f is %f degrees\n", param, result );
return 0;
}

```

```

Output

```			```
The arc tangent of 4.400000 is 77.195734 degrees

```

```

## atan function

### Example 2

```			```
#include <stdio.h>
#include <math.h>

#define PI 3.14159265

int main () {
double param, result;
param = 0.1;
result = atan(param) * 180 / PI;
printf ("The arc tangent of %f is %f degrees\n", param, result );
return 0;
}

```

```

Output

```			```
The arc tangent of 0.100000 is 5.710593 degrees

```

```